VulnerabilityPublished 22 Apr 2026Updated 21 Oct 2026

CVE-2026-31526: Linux kernel · bpf: Fix exception exit lock checking for subprogs

Affects Linux kernelSource CVE Database V5

Not known to be exploited · fixed in c0281da1f2aa5c2fca3a05f79b86bea96591c358 : update Linux kernel when convenient.

Data as of 26 Oct 2026, 12:55 UTC

Severity

Unrated

Rated by Threat Radar · No CVSS score from NVD or the CNA

EPSS: 0.1% chance of exploitation in 30 days – higher than 2% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in c0281da1f2aa5c2fca3a05f79b86bea96591c358, 6c2128505f61b504c79a20b89596feba61388112, 5a399f3117642494e35545f6ca397d3e177c1f9b +1

Exploitation evidence

Disclosed: evidence found.
CVE published 22 Apr 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.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade Linux kernel to c0281da1f2aa5c2fca3a05f79b86bea96591c358, 6c2128505f61b504c79a20b89596feba61388112, 5a399f3117642494e35545f6ca397d3e177c1f9b or 4eca06a55417c3b2e538656d12c89e224343653e.

Affected software

Product	Affected	Fixed in
LinuxLinux	Affected ≥ f18b03fabaa9b7c80e80b72a621f481f0d706ae0, < c0281da1f2aa5c2fca3a05f79b86bea96591c358	Fixed in c0281da1f2aa5c2fca3a05f79b86bea96591c358
LinuxLinux	Affected ≥ f18b03fabaa9b7c80e80b72a621f481f0d706ae0, < 6c2128505f61b504c79a20b89596feba61388112	Fixed in 6c2128505f61b504c79a20b89596feba61388112
LinuxLinux	Affected ≥ f18b03fabaa9b7c80e80b72a621f481f0d706ae0, < 5a399f3117642494e35545f6ca397d3e177c1f9b	Fixed in 5a399f3117642494e35545f6ca397d3e177c1f9b
LinuxLinux	Affected ≥ f18b03fabaa9b7c80e80b72a621f481f0d706ae0, < 4eca06a55417c3b2e538656d12c89e224343653e	Fixed in 4eca06a55417c3b2e538656d12c89e224343653e
LinuxLinux	Affected =6.7	Fixed in–

Description

In the Linux kernel, the following vulnerability has been resolved: bpf: Fix exception exit lock checking for subprogs process_bpf_exit_full() passes check_lock = !curframe to check_resource_leak(), which is false in cases when bpf_throw() is called from a static subprog. This makes check_resource_leak() to skip validation of active_rcu_locks, active_preempt_locks, and active_irq_id on exception exits from subprogs. At runtime bpf_throw() unwinds the stack via ORC without releasing any user-acquired locks, which may cause various issues as the result. Fix by setting check_lock = true for exception exits regardless of curframe, since exceptions bypass all intermediate frame cleanup. Update the error message prefix to "bpf_throw" for exception exits to distinguish them from normal BPF_EXIT. Fix reject_subprog_with_rcu_read_lock test which was previously passing for the wrong reason. Test program returned directly from the subprog call without closing the RCU section, so the error was triggered by the unclosed RCU lock on normal exit, not by bpf_throw. Update __msg annotations for affected tests to match the new "bpf_throw" error prefix. The spin_lock case is not affected because they are already checked [1] at the call site in do_check_insn() before bpf_throw can run. [1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/kernel/bpf/verifier.c?h=v7.0-rc4#n21098

References

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