TCP firewalls could be circumvented by sending a SYN Packets with other flags (like e.g. RST flag) set, which was not correctly discarded by the Linux TCP stack after firewalling.

MISC:VU#464113 | URL:https://www.kb.cert.org/vuls/id/464113 | MISC:[oss-security] 20120203 Re: CVE Request (2002): Linux TCP stack could accept invalid TCP flag combinations | URL:http://www.openwall.com/lists/oss-security/2012/02/03/7 | MISC:[oss-security] 20120529 Re: CVE Request (2002): Linux TCP stack could accept invalid TCP flag combinations | URL:http://www.openwall.com/lists/oss-security/2012/05/29/8 | MISC:[oss-security] 20120530 CVE Request -- kernel: tcp: drop SYN+FIN messages | URL:http://www.openwall.com/lists/oss-security/2012/05/30/2 | MISC:[oss-security] 20120530 Re: CVE Request -- kernel: tcp: drop SYN+FIN messages | URL:http://www.openwall.com/lists/oss-security/2012/05/30/11 | MISC:[oss-security] 20120530 Re: CVE Request -- kernel: tcp: drop SYN+FIN messages | URL:http://www.openwall.com/lists/oss-security/2012/05/30/12 | MISC:[oss-security] 20120530 Re: CVE Request -- kernel: tcp: drop SYN+FIN messages | URL:http://www.openwall.com/lists/oss-security/2012/05/30/13 | MISC:[oss-security] 20120530 Re: CVE Request -- kernel: tcp: drop SYN+FIN messages | URL:http://www.openwall.com/lists/oss-security/2012/05/30/4 | MISC:[oss-security] 20120530 Re: CVE Request -- kernel: tcp: drop SYN+FIN messages | URL:http://www.openwall.com/lists/oss-security/2012/05/30/8 | MISC:[oss-security] 20120530 Re: CVE Request -- kernel: tcp: drop SYN+FIN messages | URL:http://www.openwall.com/lists/oss-security/2012/05/30/9 | MISC:[oss-security] 20120531 Re: CVE Request -- kernel: tcp: drop SYN+FIN messages | URL:http://www.openwall.com/lists/oss-security/2012/05/31/3 | MISC:[oss-security] 20140212 Re: Old CVE ids, public, but still "RESERVED" | URL:http://www.openwall.com/lists/oss-security/2014/02/12/8 | MISC:https://bugzilla.suse.com/show_bug.cgi?id=744994%2C | URL:https://bugzilla.suse.com/show_bug.cgi?id=744994%2C | MISC:https://security.netapp.com/advisory/ntap-20210727-0003/ | URL:https://security.netapp.com/advisory/ntap-20210727-0003/ | MISC:https://www.kb.cert.org/vuls/id/464113%2C | URL:https://www.kb.cert.org/vuls/id/464113%2C | MISC:https://www.openwall.com/lists/oss-security/2012/02/03/7 | URL:https://www.openwall.com/lists/oss-security/2012/02/03/7