CVE-2026-80738: Linux kernel · bpf: Check sk_state before sk_protocol in bpf_tcp_*_syncookie
Affects Linux kernelSource CVE Database V5
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
- 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:LExploitation evidence
Disclosed: evidence found.
CVE published 3 Sep 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by 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
| Product | Affected | Fixed in |
|---|---|---|
| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| 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
- git.kernel.org/stable/c/5702e4c259809c760912c477c4ae34e9217bb4d9 (opens in a new tab)
- git.kernel.org/stable/c/b5525e853a2a08a9559adb84b0616025958dc542 (opens in a new tab)
- git.kernel.org/stable/c/22c2169770ad3b3595690e51caac875178cf496d (opens in a new tab)
- git.kernel.org/stable/c/23f682083aa3fbc0c49667818efd6979a8bc5ac2 (opens in a new tab)
- git.kernel.org/stable/c/31a420a822ff92e2090bd5d65efe8e34e2d6d9b8 (opens in a new tab)