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]'

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