CVE-2026-74597 ip6_tunnel: clear skb2->cb[] in ip6ip6_err()
A memory corruption vulnerability in the Linux kernel's IPv6 tunnel error handling allows attackers to corrupt kernel memory, potentially leading to code execution or system crashes.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-74597?
CVE-2026-74597 is a critical memory corruption vulnerability in Linux, published on 22 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
ip6_tunnel: clear skb2->cb[] in ip6ip6_err()
ip6ip6_err() clones an outer IPv6 ICMP error skb, pulls it to the quoted inner IPv6 packet, and then passes the clone to icmpv6_send(). The clone still carries the outer packet's inet6_skb_parm in skb->cb.
If the outer packet had a Home Address Option, IP6CB(skb2)->dsthao remains non-zero after skb_pull(). icmpv6_send() later calls mip6_addr_swap(), which uses that stale dsthao offset against the quoted inner packet. A malformed inner destination-options header can then make the HAO lookup and address swap run past the end of the quoted packet and corrupt skb_shared_info.
Clear skb2->cb[] before pulling the quoted inner IPv6 packet so the reply path does not reuse metadata left by the outer IPv6 stack.
Which versions are affected by CVE-2026-74597?
How do I fix CVE-2026-74597?
Apply the vendor's patch.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2026-74597 being exploited?
There is no known exploitation of CVE-2026-74597 in the wild and no public exploit code.
Sources
Also known as AZL-97350, BELL-CVE-2026-74597, DEBIAN-CVE-2026-74597, GHSA-2fqw-fh97-qvmc, UBUNTU-CVE-2026-74597.