In the Linux kernel, the following vulnerability has been resolved: net: extend IPv6 exthdr detection of tunneled packets Commit c4336a07eb6b ("net:… (CVE-2026-98852)

The Linux kernel vulnerability addressed by commit c4336a07eb6b (CVE-2026-98852) involved the net subsystem's handling of IPv6 extension headers in tunneled packets. The previous implementation split skb_gso_has_extension_hdr() based on skb->encapsulation but did not cover all code paths, causing issues such as skipping checks on outer headers for IPv6 tunnels, false positives in header length checks, and unsafe direct dereferencing of inner IPv6 headers. The fix extends detection to check ipv6_ext_hdr() on both outer and inner IPv6 headers using skb_header_pointer() for safe access, and applies the same logic in checksum offload helpers. This correction addresses checksum offload invariants for both non-GSO and GSO packets in various tunneling contexts.

The vulnerability could cause incorrect processing of tunneled IPv6 packets, leading to dropped packets or warnings due to false positives in extension header detection and unsafe header access. This may affect network performance or reliability on affected systems. There is no indication of remote code execution or privilege escalation. No known exploits in the wild have been reported.

A fix has been implemented in the Linux kernel as described in commit c4336a07eb6b. Users should update their Linux kernel to a version that includes this commit to resolve the vulnerability. Since this is a kernel-level fix, applying the official kernel update from the vendor or distribution is the recommended remediation. No additional mitigation steps are indicated.