CVE-2026-52915

Description

In the Linux kernel, the following vulnerability has been resolved: netfilter: ip6t_hbh: reject oversized option lists struct ip6t_opts stores at most IP6T_OPTS_OPTSNR option descriptors, but hbh_mt6_check() does not reject larger optsnr values supplied from userspace. Validate optsnr in the rule setup path so only match data that fits the fixed-size opts array can be installed. This follows the existing xtables pattern of rejecting invalid user-provided counts in checkentry() and keeps the packet matching path unchanged. `struct ip6t_opts` has a fixed `opts[IP6T_OPTS_OPTSNR]` array, where `IP6T_OPTS_OPTSNR` is 16, then off-by-one array access is possible: [ 137.924693][ T8692] UBSAN: array-index-out-of-bounds in ../net/ipv6/netfilter/ip6t_hbh.c:110:29 [ 137.926167][ T8692] index 16 is out of range for type '__u16 [16]'

CVSS v3.1 Score

7.1

HIGH

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H

EPSS — Exploit Prediction

0.0013

Probability of exploitation

0.03%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

References

Other References

https://git.kernel.org/stable/c/2d523ba48d4ecc46acfb6aba548292cfcce1ac02 https://git.kernel.org/stable/c/41ec2e242f1702e8370ddfe14d22b7a766021c3e https://git.kernel.org/stable/c/4322dcde6b4173c2d8e8e6118ed290794263bcc8 https://git.kernel.org/stable/c/57b0ac5e1b46f1f0338dff392ef2092e2871b412 https://git.kernel.org/stable/c/588933f1a2ca5ff99274f8c9f25dc3a25d0191c3 https://git.kernel.org/stable/c/6feb43c0995ab3a9c826707eb46541a1696fe4f7 https://git.kernel.org/stable/c/784aadea7a108c9f90985683caa87fb0198c6a39 https://git.kernel.org/stable/c/db0250470f023f159094052c0bd5ab026a88ae93

Frequently Asked Questions

What is CVE-2026-52915? +

In the Linux kernel, the following vulnerability has been resolved: netfilter: ip6t_hbh: reject oversized option lists struct ip6t_opts stores at most IP6T_OPTS_OPTSNR option descriptors, but hbh_mt6_check() does not reject larger optsnr values supplied from userspace. Validate optsnr in the rule setup path so only match data that fits the fixed-size opts array can be installed. This follows the existing xtables pattern of rejecting invalid user-provided counts in checkentry() and keeps the packet matching path unchanged. `struct ip6t_opts` has a fixed `opts[IP6T_OPTS_OPTSNR]` array, where `IP6T_OPTS_OPTSNR` is 16, then off-by-one array access is possible: [ 137.924693][ T8692] UBSAN: array-index-out-of-bounds in ../net/ipv6/netfilter/ip6t_hbh.c:110:29 [ 137.926167][ T8692] index 16 is out of range for type '__u16 [16]' It has a CVSS v3.1 base score of 7.1 (HIGH).

How severe is CVE-2026-52915? +

CVE-2026-52915 has a CVSS v3.1 score of 7.1 out of 10, rated HIGH. This is a high-severity vulnerability that should be prioritized for patching. The EPSS score is 0.0013, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-52915? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.