diff --git a/CHANGELOG.md b/CHANGELOG.md
index 0f5447b..02f5301 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -5,6 +5,7 @@
 
 * QUIC protocol check
 * bump SSLlabs rating guide to 2009r
+* Check for Opossum vulnerability
 
 ### Features implemented / improvements in 3.2
 
diff --git a/doc/testssl.1 b/doc/testssl.1
index d0fbdd9..3d23674 100644
--- a/doc/testssl.1
+++ b/doc/testssl.1
@@ -659,6 +659,9 @@ variable \f[CR]CCS_MAX_WAITSOCK\f[R].
 \f[CR]\-T, \-\-ticketbleed\f[R] Checks for Ticketbleed memory leakage in
 BigIP loadbalancers.
 .PP
+\f[CR]\-\-OP, \-\-opossum\f[R] Checks for HTTP to HTTPS upgrade
+vulnerability named Opossum.
+.PP
 \f[CR]\-\-BB, \-\-robot\f[R] Checks for vulnerability to ROBOT /
 (\f[I]Return Of Bleichenbacher\[cq]s Oracle Threat\f[R]) attack.
 .PP
@@ -1312,6 +1315,8 @@ RFC 2246: The TLS Protocol Version 1.0
 .IP \[bu] 2
 RFC 2595: Using TLS with IMAP, POP3 and ACAP
 .IP \[bu] 2
+RFC 2817: Upgrading to TLS Within HTTP/1.1
+.IP \[bu] 2
 RFC 2818: HTTP Over TLS
 .IP \[bu] 2
 RFC 2830: Lightweight Directory Access Protocol (v3): Extension for
diff --git a/doc/testssl.1.html b/doc/testssl.1.html
index 42e17c2..589a305 100644
--- a/doc/testssl.1.html
+++ b/doc/testssl.1.html
@@ -590,6 +590,8 @@
         <code>CCS_MAX_WAITSOCK</code>.</p>
         <p><code>-T, --ticketbleed</code> Checks for Ticketbleed memory
         leakage in BigIP loadbalancers.</p>
+        <p><code>--OP, --opossum</code> Checks for HTTP to HTTPS upgrade
+        vulnerability named Opossum.</p>
         <p><code>--BB, --robot</code> Checks for vulnerability to ROBOT
         / (<em>Return Of Bleichenbacher’s Oracle Threat</em>)
         attack.</p>
@@ -1131,6 +1133,7 @@
         <ul>
         <li>RFC 2246: The TLS Protocol Version 1.0</li>
         <li>RFC 2595: Using TLS with IMAP, POP3 and ACAP</li>
+        <li>RFC 2817: Upgrading to TLS Within HTTP/1.1</li>
         <li>RFC 2818: HTTP Over TLS</li>
         <li>RFC 2830: Lightweight Directory Access Protocol (v3):
         Extension for Transport Layer Security</li>
diff --git a/doc/testssl.1.md b/doc/testssl.1.md
index 5133fb1..a9c057e 100644
--- a/doc/testssl.1.md
+++ b/doc/testssl.1.md
@@ -236,9 +236,11 @@ Also for multiple server certificates are being checked for as well as for the c
 
 `-T, --ticketbleed`             Checks for Ticketbleed memory leakage in BigIP loadbalancers.
 
-`--BB, --robot`          Checks for vulnerability to ROBOT / (*Return Of Bleichenbacher's Oracle Threat*) attack.
+`--OP, --opossum`               Checks for HTTP to HTTPS upgrade vulnerability named Opossum.
 
-`--SI, --starttls-injection`          Checks for STARTTLS injection vulnerabilities (SMTP, IMAP, POP3 only). `socat` and OpenSSL >=1.1.0 is needed.
+`--BB, --robot`                 Checks for vulnerability to ROBOT / (*Return Of Bleichenbacher's Oracle Threat*) attack.
+
+`--SI, --starttls-injection`    Checks for STARTTLS injection vulnerabilities (SMTP, IMAP, POP3 only). `socat` and OpenSSL >=1.1.0 is needed.
 
 `-R, --renegotiation`           Tests renegotiation vulnerabilities. Currently there's a check for *Secure Renegotiation* and for *Secure Client-Initiated Renegotiation*. Please be aware that vulnerable servers to the latter can likely be DoSed very easily (HTTP). A check for *Insecure Client-Initiated Renegotiation* is not yet implemented.
 
@@ -490,6 +492,7 @@ Please note that for plain TLS-encrypted ports you must not specify the protocol
 
 * RFC 2246: The TLS Protocol Version 1.0
 * RFC 2595: Using TLS with IMAP, POP3 and ACAP
+* RFC 2817: Upgrading to TLS Within HTTP/1.1
 * RFC 2818: HTTP Over TLS
 * RFC 2830: Lightweight Directory Access Protocol (v3): Extension for Transport Layer Security
 * RFC 3207: SMTP Service Extension for Secure SMTP over Transport Layer Security
@@ -551,7 +554,6 @@ Please note that for plain TLS-encrypted ports you must not specify the protocol
 
 **etc/client-simulation.txt**  contains client simulation data.
 
-
 **etc/cipher-mapping.txt**  provides a mandatory file with mapping from OpenSSL cipher suites names to the ones from IANA / used in the RFCs.
 
 **etc/tls_data.txt**        provides a mandatory file for ciphers (bash sockets) and key material.
diff --git a/t/32_isHTML_valid.t b/t/32_isHTML_valid.t
index de6fee9..2f843f5 100755
--- a/t/32_isHTML_valid.t
+++ b/t/32_isHTML_valid.t
@@ -48,7 +48,7 @@ $edited_html =~ s/&apos;/'/g;
 
 $diff = diff \$edited_html, \$out;
 
-cmp_ok($edited_html, "eq", $out, "Checking if HTML file matches terminal output") or
+ok($edited_html eq $out, "Checking if HTML file matches terminal output") or
      diag ("\n%s\n", "$diff");
 
 $tests++;
@@ -82,7 +82,7 @@ $debughtml =~ s/.*Using bash .*\n//g;
 
 $diff = diff \$debughtml, \$html;
 
-cmp_ok($debughtml, "eq", $html, "Checking if HTML file created with --debug 4 matches HTML file created without --debug") or
+ok($debughtml eq $html, "Checking if HTML file created with --debug 4 matches HTML file created without --debug") or
      diag ("\n%s\n", "$diff");
 $tests++;
 
diff --git a/t/baseline_data/default_testssl.csvfile b/t/baseline_data/default_testssl.csvfile
index ee67de6..cef9b65 100644
--- a/t/baseline_data/default_testssl.csvfile
+++ b/t/baseline_data/default_testssl.csvfile
@@ -90,6 +90,7 @@
 "heartbleed","testssl.sh/81.169.166.184","443","OK","not vulnerable, no heartbeat extension","CVE-2014-0160","CWE-119"
 "CCS","testssl.sh/81.169.166.184","443","OK","not vulnerable","CVE-2014-0224","CWE-310"
 "ticketbleed","testssl.sh/81.169.166.184","443","OK","no session ticket extension","CVE-2016-9244","CWE-200"
+"opossum","testssl.sh/81.169.166.184","443","OK","not vulnerable","CVE-2025-49812","CWE-287"
 "ROBOT","testssl.sh/81.169.166.184","443","OK","not vulnerable","CVE-2017-17382 CVE-2017-17427 CVE-2017-17428 CVE-2017-13098 CVE-2017-1000385 CVE-2017-13099 CVE-2016-6883 CVE-2012-5081 CVE-2017-6168","CWE-203"
 "secure_renego","testssl.sh/81.169.166.184","443","OK","supported","","CWE-310"
 "secure_client_renego","testssl.sh/81.169.166.184","443","OK","not vulnerable","CVE-2011-1473","CWE-310"
diff --git a/testssl.sh b/testssl.sh
index 4cd80ae..d95c9c0 100755
--- a/testssl.sh
+++ b/testssl.sh
@@ -1786,12 +1786,13 @@ filter_input() {
      sed -e 's/#.*$//' -e '/^$/d' <<< "$1" | tr -d '\n' | tr -d '\t' | tr -d '\r'
 }
 
-# Dl's any URL (arg1) via HTTP 1.1 GET from port 80, arg2: file to store http body.
+# Dl any URL (arg1) via HTTP 1.1 GET from port 80 or 443 (curl/wget). arg2: file to store http body.
 # Proxy is not honored yet (see cmd line switches) -- except when using curl or wget.
-# There the environment variable is used automatically
-# Currently it is being used by check_revocation_crl() only.
+# The PROXY environment variable is used when specified
+# Currently this is being used by check_revocation_crl() only.
+#
 http_get() {
-     local proto z
+     local proto="" foo=""
      local node="" query=""
      local dl="$2"
      local useragent="$UA_STD"
@@ -1825,7 +1826,7 @@ http_get() {
           # Worst option: slower and hiccups with chunked transfers. Workaround for the
           # latter is using HTTP/1.0. We do not support https here, yet.
           # First the URL will be split
-          IFS=/ read -r proto z node query <<< "$1"
+          IFS=/ read -r proto foo node query <<< "$1"
           proto=${proto%:}
           if [[ "$proto" != http ]]; then
                pr_warning "protocol $proto not supported yet"
@@ -1844,7 +1845,7 @@ http_get() {
                     printf -- "%b" "GET $proto://$node/$query HTTP/1.0\r\nUser-Agent: $useragent\r\nHost: $node\r\nAccept: */*\r\n\r\n" >&33
                fi
           else
-               IFS=/ read -r proto z node query <<< "$1"
+               IFS=/ read -r proto foo node query <<< "$1"
                exec 33<>/dev/tcp/$node/80
                printf -- "%b" "GET /$query HTTP/1.0\r\nUser-Agent: $useragent\r\nHost: $node\r\nAccept: */*\r\n\r\n" >&33
           fi
@@ -1861,55 +1862,105 @@ http_get() {
      fi
 }
 
-# Outputs the headers when downloading any URL (arg1) via HTTP 1.1 GET from port 80.
+# Outputs the HTTP headers via HTTP 1.1 HEAD command via HTTPS and a valid certificate
+#    arg1 is the URL
+#    arg2 is optional and could be a request header. curl/wget don't send empty headers otherwise
+#
 # Only works if curl or wget is available.
-# There the environment variable is used automatically
-# Currently it is being used by check_pwnedkeys() only.
-http_get_header() {
+# The proxy environment variable is used automatically.
+# Currently it is being used by check_pwnedkeys() only
+#
+http_head() {
      local proto
      local node="" query=""
-     local dl="$2"
+     local request_header="$2"
      local useragent="$UA_STD"
-     local jsonID="http_get_header"
-     local headers
+     local response_headers=""
+     local xtra_params=""
      local -i ret
 
      "$SNEAKY" && useragent="$UA_SNEAKY"
 
      if type -p curl &>/dev/null; then
+          xtra_params="--connect-timeout $HEADER_MAXSLEEP --head -s"
           if [[ -z "$PROXY" ]]; then
-               headers="$(curl --head -s  --noproxy '*' -A $''"$useragent"'' "$1")"
+               response_headers="$(curl $xtra_params --noproxy '*' -H $''"$request_header"'' -A $''"$useragent"'' "$1")"
           else
                # for the sake of simplicity assume the proxy is using http
-               headers="$(curl --head -s -x $PROXYIP:$PROXYPORT -A $''"$useragent"'' "$1")"
+               response_headers="$(curl $xtra_params -x $PROXYIP:$PROXYPORT -H $''"$request_header"'' -A $''"$useragent"'' "$1")"
           fi
           ret=$?
-          [[ $ret -eq 0 ]] && tm_out "$headers"
+          [[ $ret -eq 0 ]] && tm_out "$response_headers"
           return $ret
      elif type -p wget &>/dev/null; then
+          xtra_params="--timeout=$HEADER_MAXSLEEP --tries=1 --cache=off"
           # wget has no proxy command line. We need to use http_proxy instead. And for the sake of simplicity
           # assume the GET protocol we query is using http -- http_proxy is the $ENV not for the connection TO
           # the proxy, but for the protocol we query THROUGH the proxy
           if [[ -z "$PROXY" ]]; then
-               headers="$(wget --no-proxy -q -S -U $''"$useragent"'' -O /dev/null "$1" 2>&1)"
+               response_headers="$(wget --no-proxy -q -S $xtra_params --header $''"$request_header"'' -U $''"$useragent"'' -O /dev/null "$1" 2>&1)"
           else
                if [[ -z "$http_proxy" ]]; then
-                    headers="$(http_proxy=http://$PROXYIP:$PROXYPORT wget -q -S  -U $''"$useragent"'' -O /dev/null "$1" 2>&1)"
+                    response_headers="$(http_proxy=http://$PROXYIP:$PROXYPORT wget -q -S $xtra_params --header $''"$request_header"'' -U $''"$useragent"'' -O /dev/null "$1" 2>&1)"
                else
-                    headers="$(wget -q -S -U $''"$useragent"'' -O /dev/null "$1" 2>&1)"
+                    response_headers="$(wget -q -S $xtra_params --header $''"$request_header"'' -U $''"$useragent"'' -O /dev/null "$1" 2>&1)"
                fi
           fi
           ret=$?
-          [[ $ret -eq 0 ]] && tm_out "$headers"
+          [[ $ret -eq 0 ]] && tm_out "$response_headers"
           # wget(1): "8: Server issued an error response.". Happens e.g. when 404 is returned. However also if the call wasn't correct (400)
           # So we assume for now that everything is submitted correctly. We parse the error code too later
-          [[ $ret -eq 8 ]] && ret=0 && tm_out "$headers"
+          [[ $ret -eq 8 ]] && ret=0 && tm_out "$response_headers"
           return $ret
      else
           return 1
      fi
 }
 
+# does a simple http head via printf with no proxy, only used by run_opossum()
+#    arg1: URL
+#    arg2: extra http header
+#
+# return codes:
+#    0: all fine
+#    1: server dind't respond within HEADER_MAXSLEEP
+#    3: server dind't respond within HEADER_MAXSLEEP and PROXY was defined
+#
+http_header_printf() {
+     local request_header="$2"
+     local useragent="$UA_STD"
+     local tmpfile=$TEMPDIR/$NODE.$NODEIP.http_header_printf.log
+     local errfile=$TEMPDIR/$NODE.$NODEIP.http_header_printf-err.log
+     local -i ret=0
+     local proto="" foo="" node="" query=""
+
+     [[ $DEBUG -eq 0 ]] && errfile=/dev/null
+
+     IFS=/ read -r proto foo node query <<< "$1"
+     exec 33<>/dev/tcp/$node/80
+     printf -- "%b" "HEAD ${proto}//${node}/${query} HTTP/1.1\r\nUser-Agent: ${useragent}\r\nHost: ${node}\r\n${request_header}\r\nAccept: */*\r\n\r\n\r\n" >&33 2>$errfile &
+     wait_kill $! $HEADER_MAXSLEEP
+     if [[ $? -ne 0 ]]; then
+          # not killed
+          if [[ -n "$PROXY" ]]; then
+               ret=3
+          fi
+          ret=1
+     else
+          ret=0
+     fi
+     if [[ $DEBUG -eq 0 ]] ; then
+          cat <&33
+     else
+          cat <&33 >$tmpfile
+          cat $tmpfile
+     fi
+     exec 33<&-
+     exec 33>&-
+     return $ret
+}
+
+
 ldap_get() {
      local ldif
      local -i success
@@ -1940,6 +1991,7 @@ ldap_get() {
 #     1 - key not found in database
 #     2 - key found in database
 #     7 - network/proxy failure
+#
 check_pwnedkeys() {
      local cert="$1"
      local cert_key_algo="$2"
@@ -1969,7 +2021,7 @@ check_pwnedkeys() {
      fi
      fingerprint="$($OPENSSL pkey -pubin -outform DER <<< "$pubkey" 2>/dev/null | $OPENSSL dgst -sha256 -hex 2>/dev/null)"
      fingerprint="${fingerprint#*= }"
-     response="$(http_get_header "https://v1.pwnedkeys.com/$fingerprint")"
+     response="$(http_head "https://v1.pwnedkeys.com/$fingerprint")"
      # Handle curl's/wget's connectivity exit codes
      case $? in
           4|5|7)     return 7 ;;
@@ -9927,7 +9979,7 @@ certificate_info() {
           check_pwnedkeys "$HOSTCERT" "$cert_key_algo" "$cert_keysize"
           case "$?" in
                0) outln "not checked"; fileout "pwnedkeys${json_postfix}" "INFO" "not checked" ;;
-               1) outln "not in database"; fileout "pwnedkeys${json_postfix}" "INFO" "not in database" ;;
+               1) pr_svrty_good "not in database"; fileout "pwnedkeys${json_postfix}" "OK" "not in database" ;;
                2) pr_svrty_critical "NOT ok --"; outln " key appears in database"; fileout "pwnedkeys${json_postfix}" "CRITICAL" "private key is known" ;;
                7) prln_warning "error querying https://v1.pwnedkeys.com"; fileout "pwnedkeys${json_postfix}" "WARN" "connection error" ;;
           esac
@@ -12212,6 +12264,7 @@ code2network() {
 # sockets inspired by https://blog.chris007.de/using-bash-for-network-socket-operation/
 # ARG1: hexbytes separated by commas, with a leading comma
 # ARG2: seconds to sleep
+#
 socksend_clienthello() {
      local data=""
 
@@ -12230,6 +12283,7 @@ socksend_clienthello() {
 
 # ARG1: hexbytes -- preceded by x -- separated by commas, with a leading comma
 # ARG2: seconds to sleep
+#
 socksend() {
      local data line
 
@@ -17339,6 +17393,7 @@ run_ccs_injection(){
 
 
 # see https://blog.filippo.io/finding-ticketbleed/ |  https://filippo.io/ticketbleed/
+#
 run_ticketbleed() {
      local tls_hexcode tls_proto=""
      local sessticket_tls="" session_tckt_tls=""
@@ -17363,7 +17418,7 @@ run_ticketbleed() {
      pr_bold " Ticketbleed"; out " ($cve), experiment.  "
 
      if [[ "$SERVICE" != HTTP ]] && [[ "$CLIENT_AUTH" != required ]]; then
-          outln "(applicable only for HTTPS)"
+          outln "(applicable only for HTTP service)"
           fileout "$jsonID" "INFO" "not applicable, not HTTP" "$cve" "$cwe"
           return 0
      fi
@@ -17625,6 +17680,55 @@ run_ticketbleed() {
      return $ret
 }
 
+# https://opossum-attack.com/, TLS Upgrade via old RFC 2817
+#
+run_opossum() {
+     local cve='CVE-2025-49812'
+     local jsonID="opossum"
+     local cwe="CWE-287"
+     local -i ret=0
+     local uri=$URI
+     local service="$SERVICE"
+     local response=""
+
+     [[ -n "$STARTTLS" ]] && return 0
+     [[ $VULN_COUNT -le $VULN_THRESHLD ]] && outln && pr_headlineln " Testing for Opossum vulnerability " && outln
+     pr_bold " Opossum"; out " ($cve)                  "
+
+     # we're trying to connect also if ASSUME_HTTP is not set, there should be either one of following hints though
+     if [[ -z $service ]]; then
+          [[ $uri =~ ^http ]] && service=HTTP                    # https provided as target/URL
+          [[ "$CLIENT_AUTH" == required ]] && service=HTTP       # also try when client auth is requested (we dont use it over cleartext)
+     fi
+     case $service in
+          HTTP)
+               uri=${URI/https:\/\//}
+               response=$(http_header_printf http://${uri} 'Upgrade: TLS/1.0\r\n\r\nClose\r\n')
+               # In any case we use $response but we handle the return codes
+               case $? in
+                    0)   ret=0 ;;
+                    1|3) ret=7 ;;       # got stuck
+               esac
+               if [[ $response =~ Upgrade:\ TLS ]]; then
+                    prln_svrty_high "VULNERABLE (NOT ok)"
+                    fileout "$jsonID" "CRITICAL" "VULNERABLE" "$cve" "$cwe" "$hint"
+               else
+                    prln_svrty_good "not vulnerable (OK)"
+                    fileout "$jsonID" "OK" "not vulnerable $append" "$cve" "$cwe"
+               fi
+          ;;
+          IMAP|FTP|POP3|SMTP|LMTP|NNTP)
+               outln "(implemented currently for HTTP only)"
+               fileout "$jsonID" "INFO" "not yet implemented" "$cve" "$cwe"
+               ;;
+          *)   outln "(applicable only for HTTP service)"
+               fileout "$jsonID" "INFO" "not applicable, not HTTP" "$cve" "$cwe"
+               ;;
+     esac
+     return $ret
+}
+
+
 # Overview @ http://www.exploresecurity.com/wp-content/uploads/custom/SSL_manual_cheatsheet.html
 #
 run_renego() {
@@ -21257,6 +21361,7 @@ single check as <options>  ("$PROG_NAME URI" does everything except -E and -g):
      -H, --heartbleed              tests for Heartbleed vulnerability
      -I, --ccs, --ccs-injection    tests for CCS injection vulnerability
      -T, --ticketbleed             tests for Ticketbleed vulnerability in BigIP loadbalancers
+     --OP, --opossum               tests for Opossum vulnerability
      --BB, --robot                 tests for Return of Bleichenbacher's Oracle Threat (ROBOT) vulnerability
      --SI, --starttls-injection    tests for STARTTLS injection issues
      -R, --renegotiation           tests for renegotiation vulnerabilities
@@ -23980,6 +24085,7 @@ initialize_globals() {
      do_breach=false
      do_ccs_injection=false
      do_ticketbleed=false
+     do_opossum=false
      do_robot=false
      do_cipher_per_proto=false
      do_crime=false
@@ -24028,6 +24134,7 @@ set_scanning_defaults() {
      do_heartbleed="$OFFENSIVE"
      do_ccs_injection="$OFFENSIVE"
      do_ticketbleed="$OFFENSIVE"
+     do_opossum=true
      do_robot="$OFFENSIVE"
      do_crime=true
      do_freak=true
@@ -24048,9 +24155,9 @@ set_scanning_defaults() {
      do_tls_fallback_scsv=true
      do_client_simulation=true
      if "$OFFENSIVE"; then
-          VULN_COUNT=17
+          VULN_COUNT=18
      else
-          VULN_COUNT=13
+          VULN_COUNT=14
      fi
      do_rating=true
 }
@@ -24061,10 +24168,10 @@ count_do_variables() {
      local -i true_nr=0
 
      for gbl in do_allciphers do_vulnerabilities do_beast do_lucky13 do_breach do_ccs_injection do_ticketbleed do_cipher_per_proto do_crime \
-               do_freak do_logjam do_drown do_header do_heartbleed do_mx_all_ips do_fs do_protocols do_rc4 do_starttls_injection do_grease do_robot do_renego \
-               do_cipherlists do_server_defaults do_server_preference do_ssl_poodle do_tls_fallback_scsv do_winshock \
-               do_sweet32 do_client_simulation do_cipher_match do_tls_sockets do_mass_testing do_display_only do_rating; do
-                    "${!gbl}" && ((true_nr++))
+          do_freak do_logjam do_drown do_header do_heartbleed do_mx_all_ips do_fs do_protocols do_rc4 do_starttls_injection do_grease \
+          do_opossum do_robot do_renego do_cipherlists do_server_defaults do_server_preference do_ssl_poodle do_tls_fallback_scsv \
+          do_winshock  do_sweet32 do_client_simulation do_cipher_match do_tls_sockets do_mass_testing do_display_only do_rating; do
+               "${!gbl}" && ((true_nr++))
      done
      return $true_nr
 }
@@ -24074,10 +24181,10 @@ debug_globals() {
      local gbl
 
      for gbl in do_allciphers do_vulnerabilities do_beast do_lucky13 do_breach do_ccs_injection do_ticketbleed do_cipher_per_proto do_crime \
-               do_freak do_logjam do_drown do_header do_heartbleed do_mx_all_ips do_fs do_protocols do_rc4 do_starttls_injection do_grease do_robot do_renego \
-               do_cipherlists do_server_defaults do_server_preference do_ssl_poodle do_tls_fallback_scsv do_winshock \
-               do_sweet32 do_client_simulation do_cipher_match do_tls_sockets do_mass_testing do_display_only do_rating; do
-          printf "%-22s = %s\n" $gbl "${!gbl}"
+          do_freak do_logjam do_drown do_header do_heartbleed do_mx_all_ips do_fs do_protocols do_rc4 do_starttls_injection do_grease\
+          do_opossum do_robot do_renego do_cipherlists do_server_defaults do_server_preference do_ssl_poodle do_tls_fallback_scsv \
+          do_winshock do_sweet32 do_client_simulation do_cipher_match do_tls_sockets do_mass_testing do_display_only do_rating; do
+               printf "%-22s = %s\n" $gbl "${!gbl}"
      done
      # ${!var} is an indirect expansion, see https://www.gnu.org/software/bash/manual/html_node/Shell-Parameter-Expansion.html
      # Example: https://stackoverflow.com/questions/8515411/what-is-indirect-expansion-what-does-var-mean#8515492
@@ -24283,6 +24390,7 @@ parse_cmd_line() {
                     do_heartbleed="$OFFENSIVE"
                     do_ccs_injection="$OFFENSIVE"
                     do_ticketbleed="$OFFENSIVE"
+                    do_opossum=true
                     do_robot="$OFFENSIVE"
                     do_renego=true
                     do_crime=true
@@ -24299,9 +24407,9 @@ parse_cmd_line() {
                     do_rc4=true
                     do_starttls_injection=true
                     if "$OFFENSIVE"; then
-                         VULN_COUNT=17
+                         VULN_COUNT=18
                     else
-                         VULN_COUNT=13
+                         VULN_COUNT=14
                     fi
                     ;;
                --ids-friendly)
@@ -24319,6 +24427,10 @@ parse_cmd_line() {
                     do_ticketbleed=true
                     ((VULN_COUNT++))
                     ;;
+               --OP|--opossum)
+                    do_opossum=true
+                    ((VULN_COUNT++))
+                    ;;
                -BB|--BB|--robot)
                     do_robot=true
                     ;;
@@ -24984,6 +25096,7 @@ lets_roll() {
                "$do_heartbleed" && { run_heartbleed; ret=$(($? + ret)); stopwatch run_heartbleed; }
                "$do_ccs_injection" && { run_ccs_injection; ret=$(($? + ret)); stopwatch run_ccs_injection; }
                "$do_ticketbleed" && { run_ticketbleed; ret=$(($? + ret)); stopwatch run_ticketbleed; }
+               "$do_opossum" && { run_opossum; ret=$(($? + ret)); stopwatch run_opossum; }
                "$do_robot" && { run_robot; ret=$(($? + ret)); stopwatch run_robot; }
                "$do_renego" && { run_renego; ret=$(($? + ret)); stopwatch run_renego; }
                "$do_crime" && { run_crime; ret=$(($? + ret)); stopwatch run_crime; }