Out-of-bounds write in Linux kernel - CVE-2026-98371

Vulnerability details

The vulnerability allows a remote attacker to cause a denial of service.

The vulnerability exists due to an out-of-bounds write in the Linux kernel IPTFS function iptfs_reassem_cont() when reassembling an inner IP packet whose declared length is smaller than its minimum header size. A remote attacker can send specially crafted outer packets that split the inner IPv4 header across two packets and declare an inner total length between 6 and 19 bytes to cause a denial of service.

Remote exploitation targets IPTFS VPN gateways and requires the decrypted outer socket buffer to be linear, as can occur with AF_PACKET taps or tun/tap delivery. The socket buffer tailroom check triggers a kernel panic.

Affected software

How to mitigate CVE-2026-98371

External References

• https://git.kernel.org/stable/c/5b8afb56ccb7c014b0f1ac40341708b200443c2d
• https://git.kernel.org/stable/c/a7018ee0ea8622ed59edc064be4e0f2c26464f53
• https://git.kernel.org/stable/c/dc33262be1fe43d0eb0b84fb58c6ed42e2f64a8c

Related Security Bulletins

• Out-of-bounds write in Linux kernel xfrm
• Ubuntu update for linux-oem-7.0
• Ubuntu update for linux, linux-aws, linux-gcp and more