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VulnerabilityPublished Updated

CVE-2026-80738: Linux kernel · bpf: Check sk_state before sk_protocol in bpf_tcp_*_syncookie

Affects Linux kernelSource CVE Database V5

0

Not known to be exploited · CVSS 7.3 High · fixed in b5525e853a2a08a9559adb84b0616025958dc542 : patch Linux kernel soon.

Data as of 26 Oct 2026, 13:47 UTC

CVSS 3.1 base score
7.3High
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.1% chance of exploitation in 30 days – higher than 6% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in b5525e853a2a08a9559adb84b0616025958dc542, 5702e4c259809c760912c477c4ae34e9217bb4d9, 31a420a822ff92e2090bd5d65efe8e34e2d6d9b8 +2
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:L

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 3 Sep 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

What to do

Upgrade to a fixed release listed under Affected software.

Affected software

ProductAffectedFixed in
LinuxLinuxAffected
  • ≥ 399040847084a69f345e0a52fd62f04654e0fce3, < b5525e853a2a08a9559adb84b0616025958dc542
Fixed in
  • b5525e853a2a08a9559adb84b0616025958dc542
LinuxLinuxAffected
  • ≥ 399040847084a69f345e0a52fd62f04654e0fce3, < 5702e4c259809c760912c477c4ae34e9217bb4d9
Fixed in
  • 5702e4c259809c760912c477c4ae34e9217bb4d9
LinuxLinuxAffected
  • ≥ 399040847084a69f345e0a52fd62f04654e0fce3, < 31a420a822ff92e2090bd5d65efe8e34e2d6d9b8
Fixed in
  • 31a420a822ff92e2090bd5d65efe8e34e2d6d9b8
LinuxLinuxAffected
  • ≥ 399040847084a69f345e0a52fd62f04654e0fce3, < 23f682083aa3fbc0c49667818efd6979a8bc5ac2
Fixed in
  • 23f682083aa3fbc0c49667818efd6979a8bc5ac2
LinuxLinuxAffected
  • ≥ 399040847084a69f345e0a52fd62f04654e0fce3, < 22c2169770ad3b3595690e51caac875178cf496d
Fixed in
  • 22c2169770ad3b3595690e51caac875178cf496d
LinuxLinuxAffected
  • =5.2
Fixed in–

Description

In the Linux kernel, the following vulnerability has been resolved: bpf: Check sk_state before sk_protocol in bpf_tcp_*_syncookie bpf_tcp_gen_syncookie and bpf_tcp_check_syncookie accept a socket pointer 'sk' with argument type ARG_PTR_TO_BTF_ID_SOCK_COMMON. However, they access sk->sk_protocol without validating whether 'sk' represents a full socket. Fix this issue by checking sk->sk_state != TCP_LISTEN before inspecting sk->sk_protocol in both bpf_tcp_gen_syncookie and bpf_tcp_check_syncookie. Since mini-sockets are never in the TCP_LISTEN state, the condition short-circuits and prevents dereferencing fullsock-specific fields.

References

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