Vulnerability in Linux

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.

Published .

CVSS v3 metric

CVSS v3 base score 9.3 (Critical). Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H.

EPSS exploit prediction

No EPSS score from FIRST.org yet. New CVEs usually get one within a few days; no score means no signal yet, not low risk. How EPSS works.

Affected products

  • Linux — versions 2.6.27

References

Frequently asked questions

What is CVE-2026-99999?
CVE-2026-99999 is a critical-severity vulnerability in Linux. CVSS score: 9.3/10. Published 2026-10-15.
How severe is CVE-2026-99999?
Critical severity. CVSS v3 base score is 9.3 out of 10.