VulnerabilityPublished 14 Oct 2026Updated 19 Oct 2026

CVE-2026-98398: Linux kernel · locking/lockdep: Invalidate stale class_cache entries for zapped classes

Affects Linux kernelSource CVE Database V5

Not known to be exploited · fixed in f63c86e9d267629758adaba18579e784ddd63c32 : update Linux kernel when convenient.

Data as of 26 Oct 2026, 12:55 UTC

Severity

Medium

Rated Medium by Threat Radar's AI analysis · CVSS not yet scored by NVD

EPSS: 0.2% chance of exploitation in 30 days – higher than 10% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in f63c86e9d267629758adaba18579e784ddd63c32, f8a1281ab82df5b51fd0384354d4b21daf2b7af0, c7acfb04c7e2e2dea248282b21373d93296644dd +4

Exploitation evidence

Disclosed: evidence found.
CVE published 14 Oct 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 to a fixed release listed under Affected software.

Affected software

Product	Affected	Fixed in
LinuxLinux	Affected ≥ a0b0fd53e1e67639b303b15939b9c653dbe7a8c4, < f63c86e9d267629758adaba18579e784ddd63c32	Fixed in f63c86e9d267629758adaba18579e784ddd63c32
LinuxLinux	Affected ≥ a0b0fd53e1e67639b303b15939b9c653dbe7a8c4, < f8a1281ab82df5b51fd0384354d4b21daf2b7af0	Fixed in f8a1281ab82df5b51fd0384354d4b21daf2b7af0
LinuxLinux	Affected ≥ a0b0fd53e1e67639b303b15939b9c653dbe7a8c4, < c7acfb04c7e2e2dea248282b21373d93296644dd	Fixed in c7acfb04c7e2e2dea248282b21373d93296644dd
LinuxLinux	Affected ≥ a0b0fd53e1e67639b303b15939b9c653dbe7a8c4, < baa320fbb2f9fea50f5632a307da8ce84fbef5bd	Fixed in baa320fbb2f9fea50f5632a307da8ce84fbef5bd
LinuxLinux	Affected ≥ a0b0fd53e1e67639b303b15939b9c653dbe7a8c4, < 6bc345f6d81ebe22e0f355c2a21d7e29691f9332	Fixed in 6bc345f6d81ebe22e0f355c2a21d7e29691f9332
LinuxLinux	Affected ≥ a0b0fd53e1e67639b303b15939b9c653dbe7a8c4, < 02c6be7d675b21d81f0ba3a524346850a8c0e3bf	Fixed in 02c6be7d675b21d81f0ba3a524346850a8c0e3bf

AI-suggested

A fix is available and has been applied in the Linux kernel commits identified by hashes f63c86e9d267629758adaba18579e784ddd63c32, f8a1281ab82df5b51fd0384354d4b21daf2b7af0, c7acfb04c7e2e2dea248282b21373d93296644dd, baa320fbb2f9fea50f5632a307da8ce84fbef5bd, 6bc345f6d81ebe22e0f355c2a21d7e29691f9332, 02c6be7d675b21d81f0ba3a524346850a8c0e3bf, and 1c9d664e2e067fca69e5a41d68e23bbc66a583fe. Users and administrators should update to a kernel version including these fixes to resolve the issue. No additional mitigation steps are indicated.

Description

CVE-2026-98398 is a vulnerability in the Linux kernel's locking/lockdep subsystem where stale class_cache entries for zapped lock classes are not invalidated properly. This can cause lockdep warnings and potential ABA issues when a stale cache entry matches a newly allocated unrelated lock key. The issue arises when lock classes are zapped during module unload or key unregistration but existing lockdep_map instances still hold pointers to these invalid classes. The vulnerability has been fixed by adding validation checks for cached classes and ensuring stale entries fall back to proper registration.

Impact

This vulnerability can cause kernel warnings and instability due to invalid lock class indices during lock acquisition. It may also lead to ABA issues where a stale cached lock class erroneously matches a different lock key, potentially affecting kernel locking correctness. There is no indication of direct exploitation or remote attack, but it affects kernel reliability and correctness.

Summary

The Linux kernel's lockdep system had a flaw where stale class_cache entries for zapped lock classes were not invalidated. When a lock class is zapped, its bit is cleared and it is removed from the class hash table, but existing lockdep_map instances may still reference the invalid class. Subsequent lock acquisitions could then use these stale entries, causing warnings due to invalid class indices and potentially leading to ABA issues if the zapped slot is reallocated to an unrelated lock key. The fix involves validating cached classes with lock_class_cache_is_valid(), using safe atomic accessors, and falling back to register_lock_class() if the cache is invalid.

References

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 26 Oct 2026, 11:33 UTC

Technical details

References

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