CVE-2026-80976

/// Technical description

In the Linux kernel, the following vulnerability has been resolved:

seg6: reset IP6CB after IPv6 decapsulation

decap_and_validate() pulls the outer SRv6 headers and makes the inner

packet the skb network header. The IPv6 control block still contains

values collected while parsing the outer packet, including nhoff and

extension-header flags.

End.DX6 and End.DT6 route the inner IPv6 packet directly to the IPv6

input path. An unprivileged user can reach End.DT6 from a user and net

namespace by installing a local SID and injecting an outer packet with

Hop-by-Hop and Destination Options headers followed by an SRH and a

minimal inner IPv6 packet.

The outer extension headers leave a large nhoff in IP6CB. After

decapsulation, ip6_protocol_deliver_rcu() uses that stale offset on the

inner packet and reads beyond the skb head. KASAN reports:

BUG: KASAN: slab-out-of-bounds in ip6_protocol_deliver_rcu

ip6_protocol_deliver_rcu+0x1118/0x1450

ip6_input_finish+0x11b/0x240

seg6_local_input

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References