CVE-2026-99999

In the Linux kernel, the following vulnerability has been resolved: ipv4: validate checksum_start before completing checksum If a packet with bad checksum metadata gets into the ipv4 stack, skb_checksum_help can corrupt the network header and cause a bunch of mischief. This was discovered and reported by Paulos, and has been reporoduced by others independently since. We really shouldn't allow such packets in, but as a defence in depth measure, let's also check before we complete the checksum. A more complete validation at input is forthcoming, but needs more work.

CVSS

9.3

EPSS

—

CISA KEV

Not listed

Exploitation

No report

Public exploits

None seen

State

PUBLISHED

Coverage

• LWN.net◆Authoritative. Authoritative publisher: a primary source, or a newsroom with formal editorial standards2 hours ago

  Seven stable kernels for Thursday with fix for critical vulnerability

  Greg Kroah-Hartman has announced the release of the 7.2.11, 6.18.57, 6.12.113, 6.6.159, 6.1.190, 5.15.223, and 5.10.272 stable kernels. This series includes, among other things, a fix for a critical vulnerability (CVE-2026-99999). The flaw in skb_checksum_help() would allow an IPv4 packet with bad…

  ↗lwn.net/Articles/1100611(opens the publisher's site in a new tab)

What we observed