Improper input validation in Linux kernel - CVE-2026-99999

Vulnerability details

The vulnerability allows a remote attacker to corrupt IPv4 packet headers and potentially compromise system confidentiality, integrity, and availability.

The vulnerability exists due to improper validation of the checksum start offset in the Linux kernel IPv4 checksum-completion paths when processing packets with invalid checksum metadata. A remote attacker can introduce a packet whose checksum start offset precedes the end of its IPv4 header into an affected processing path to cause skb_checksum_help to corrupt the network header, potentially compromising system confidentiality, integrity, and availability.

Affected software

How to mitigate CVE-2026-99999

External References

• https://git.kernel.org/stable/c/0fab003ef4698e0628060a45a48f14b43ba2a40a
• https://git.kernel.org/stable/c/32a8b0adaa18e52aaa0b246b5ffe683075354dbb
• https://git.kernel.org/stable/c/6785011f8b16abf40b1e9d8b2e332232b3e68822
• https://git.kernel.org/stable/c/94524b7b32691de2e2ce162c04d6cbc9106e5cbf
• https://git.kernel.org/stable/c/a464d950f31c89565cbaae038cc60db04fe01956
• https://git.kernel.org/stable/c/a65f69e0f38ffbed1b128029e09097436416dc8b
• https://git.kernel.org/stable/c/c3e33464746166264334641dc850a36eef7e6326
• https://git.kernel.org/stable/c/f3e835af6226f1dd12160cbd696081e9b6155de0
• https://pwn.ai/blog/Pwnescape
• https://vercel.com/blog/findings-from-the-1-million-dollar-vercel-sandbox-challenge
• http://www.openwall.com/lists/oss-security/2026/10/15/5

Related Security Bulletins

• Improper input validation in Linux kernel xfrm
• Fedora 45 update for kernel
• Fedora 43 update for kernel
• Debian update for linux