Out-of-bounds Read in Linux

CVE-2026-23455

In the Linux kernel, the following vulnerability has been resolved: netfilter: nf_conntrack_h323: check for zero length in DecodeQ931() In DecodeQ931(), the UserUserIE code path reads a 16-bit length from the packet, then decrements it by 1 to skip the protocol discriminator byte before passing it to DecodeH323_UserInformation(). If the encoded length is 0, the decrement wraps to -1, which is then passed as a large value to the decoder, leading to an out-of-bounds read. Add a check to ensure len is positive after the decrement.

Vulnerability class: Buffer Overflow

Published · last modified .

CVSS v3 metric

CVSS v3 base score 9.1 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H.

EPSS exploit prediction

EPSS: 0.013 (70.3th percentile), scored .

Low probability of exploitation in the next 30 days, but still tracked. 70th percentile — 70.3% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS trend (30 days)EPSS over the last 30 days for CVE-2026-23455: held from 0.013 to 0.013.

EPSS over last 30 days · oldest: 0.013 · newest: 0.013 · change: 0.000

Affected products

  • Linux — versions 5e35941d990123f155b02d5663e51a24f816b6f3, 2.6.17, 0
  • Linux Kernel — versions 7.0

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2026-23455?
CVE-2026-23455 is a critical-severity vulnerability in Linux, classified under Out-of-bounds Read. CVSS score: 9.1/10. Published 2026-04-03.
How severe is CVE-2026-23455?
Critical severity. CVSS v3 base score is 9.1 out of 10.