CVE-2026-43038
Description
In the Linux kernel, the following vulnerability has been resolved: ipv6: icmp: clear skb2->cb[] in ip6_err_gen_icmpv6_unreach() Sashiko AI-review observed: In ip6_err_gen_icmpv6_unreach(), the skb is an outer IPv4 ICMP error packet where its cb contains an IPv4 inet_skb_parm. When skb is cloned into skb2 and passed to icmp6_send(), it uses IP6CB(skb2). IP6CB interprets the IPv4 inet_skb_parm as an inet6_skb_parm. The cipso offset in inet_skb_parm.opt directly overlaps with dsthao in inet6_skb_parm at offset 18. If an attacker sends a forged ICMPv4 error with a CIPSO IP option, dsthao would be a non-zero offset. Inside icmp6_send(), mip6_addr_swap() is called and uses ipv6_find_tlv(skb, opt->dsthao, IPV6_TLV_HAO). This would scan the inner, attacker-controlled IPv6 packet starting at that offset, potentially returning a fake TLV without checking if the remaining packet length can hold the full 18-byte struct ipv6_destopt_hao. Could mip6_addr_swap() then perform a 16-byte swap that extends past the end of the packet data into skb_shared_info? Should the cb array also be cleared in ip6_err_gen_icmpv6_unreach() and ip6ip6_err() to prevent this? This patch implements the first suggestion. I am not sure if ip6ip6_err() needs to be changed. A separate patch would be better anyway.
Predictions
Heuristic predictions, AS-IS, for prioritization only.
Mitigations
No mitigations published for this CVE yet.
The vendor-content worker queues fetches as references arrive (check back in a few minutes). Or — if you've already worked around this in production — publish your fix to the community-verified tier.
✚ Propose a mitigation on Community → Mitigations published via the community go through AI scoring + 2 human reviewers + 7-day silent objection window before landing here withsource_tier=community-verified.
OS impact
Linux kernel Affected 3 releases
| Version | Status | Fixed in |
|---|---|---|
| 7.0 | Affected | — |
| 3.13 | Affected | — |
| — | Affected | 5.10.253 |
SUSE Affected 1 release
| Version | Status | Fixed in |
|---|---|---|
| — | Affected | — |
Debian Fixed 5 releases
| Version | Status | Fixed in |
|---|---|---|
| trixie | Fixed | 6.12.85-1 |
| sid | Fixed | 6.19.12-1 |
| forky | Fixed | 6.19.12-1 |
| bullseye | Fixed | 6.1.170-1~deb11u1 |
| bookworm | Fixed | 6.1.170-1 |
Application impact
| Vendor | Product | Versions | Fixed |
|---|---|---|---|
| gcp | | |
References
- https://git.kernel.org/stable/c/0452b6526b2f54b2413b9cb4ff1ea2ac542c99c7
- https://git.kernel.org/stable/c/1ceeebd5bd6d855b17a5df625109bfe29129d7cf
- https://git.kernel.org/stable/c/3d5127d998de617b130aae96b138dba22ac6a8a7
- https://git.kernel.org/stable/c/86ab3e55673a7a49a841838776f1ab18d23a67b5
- https://git.kernel.org/stable/c/a2edbb6393972a02114b6003953a5cef3104fada
- https://git.kernel.org/stable/c/a4437faf135da293d16fcc4cc607316742bd0ebb
- https://git.kernel.org/stable/c/c438ba010171b70bad22fc18b1d5bdc3627476e8
- https://git.kernel.org/stable/c/e41953e7d118e2702bcb217879c173d9d1d3cd4e
- https://www.suse.com/security/cve/CVE-2026-43038.html
- https://security-tracker.debian.org/tracker/CVE-2026-43038
Community-verified mitigations for this CVE will appear above when contributors publish them.
Verify integrity in audit chain (admin only). AS-IS.