Is there a public exploit for CVE-2026-99256?

No public exploit for CVE-2026-99256 was found in Exploit-DB, Metasploit, Nuclei templates or public proof-of-concept repositories. That is an absence of evidence rather than proof that none exists.

What does CVE-2026-99256 affect?

CVE-2026-99256 affects Linux Linux.

— Unscored

In the Linux kernel, the following vulnerability has been resolved: dm cache: fix issue with background work locking dm cache used a…

CVE-2026-99256

In the Linux kernel, the following vulnerability has been resolved: dm cache: fix issue with background work locking dm cache used a rwsemaphore for backgroundworklock. Write locks on rwsemaphores have strict owner semantics, but there was no guarantee that the process that locked backgroundworklock was the same process that unlocked it. This can be easily seen using a kernel compiled with CONFIGDEBUGRWSEMS. Given a dm cache device , run: 'dmsetup suspend && dmsetup resume '. This will trigger a kernel warning: DEBUGRWSEMSWARNON((rwsemowner(sem) != current) && !rwsemtestoflags(sem, RWSEMNONSPINNABLE)) triggered by cacheresume(). To fix this, switch from a rwsemaphore to a spinlock and a wait queue. dm cache already has a wait queue and associated counter, migrationwait and nrallocatedmigrations, that was getting woken up when background work was getting completed, but wasn't actually used by anything. This is replaced by the backgroundwork queue and counter.

Assessment

CVSS: Not yet scored
Severity: Unscored
Known exploited: Not listed in CISA KEV
Exploit availability: Nothing found in Exploit-DB, Metasploit, Nuclei or public PoC repositories
Published: 3 November 2026
Last updated: 3 November 2026
Affected: Linux · Linux
Assigner: Linux

At the source

EUVD (ENISA)

References

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