Linux Kernel IPv4 Checksum Validation Vulnerability (CVE-2026-99999)
CVE-2026-99999 Published on October 15, 2026
ipv4: validate checksum_start before completing checksum
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.
Products Associated with CVE-2026-99999
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Affected Versions
Linux:- Version f43798c27684ab925adde7d8acc34c78c6e50df8 and below a464d950f31c89565cbaae038cc60db04fe01956 is affected.
- Version f43798c27684ab925adde7d8acc34c78c6e50df8 and below 0fab003ef4698e0628060a45a48f14b43ba2a40a is affected.
- Version f43798c27684ab925adde7d8acc34c78c6e50df8 and below 94524b7b32691de2e2ce162c04d6cbc9106e5cbf is affected.
- Version f43798c27684ab925adde7d8acc34c78c6e50df8 and below a65f69e0f38ffbed1b128029e09097436416dc8b is affected.
- Version f43798c27684ab925adde7d8acc34c78c6e50df8 and below 32a8b0adaa18e52aaa0b246b5ffe683075354dbb is affected.
- Version f43798c27684ab925adde7d8acc34c78c6e50df8 and below f3e835af6226f1dd12160cbd696081e9b6155de0 is affected.
- Version f43798c27684ab925adde7d8acc34c78c6e50df8 and below c3e33464746166264334641dc850a36eef7e6326 is affected.
- Version f43798c27684ab925adde7d8acc34c78c6e50df8 and below 6785011f8b16abf40b1e9d8b2e332232b3e68822 is affected.
- Version 2.6.27 is affected.
- Before 2.6.27 is unaffected.
- Version 5.10.272, <= 5.10.* is unaffected.
- Version 5.15.223, <= 5.15.* is unaffected.
- Version 6.1.190, <= 6.1.* is unaffected.
- Version 6.6.159, <= 6.6.* is unaffected.
- Version 6.12.113, <= 6.12.* is unaffected.
- Version 6.18.57, <= 6.18.* is unaffected.
- Version 7.2.11, <= 7.2.* is unaffected.
- Version 7.3-rc7, <= * is unaffected.