VulnerabilityPublished 28 Oct 2026

CVE-2026-99169: Linux kernel · futex: Fix mm reuse handling for FUT_OFF_MMSHARED

Source GCVE Database

Authoritative record:CVE-2026-99169

Not known to be exploited · fixed in c17cc2027773e8e4913c5ab0fe3a489b1ed5bf81 : update Linux kernel when convenient.

Data as of 28 Oct 2026, 13:57 UTC

Severity

Medium

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

Patch: Available – fixed in c17cc2027773e8e4913c5ab0fe3a489b1ed5bf81, 3267512ad1c2cc0c7768c5b014dc2cceb398a801, 2855ddc6844f527e375e78afb55ec2a5182f23b3

Exploitation evidence

Disclosed: evidence found.
CVE published 28 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.

ghsa-8p9g-5mhx-rvh4

What to do

Upgrade Linux kernel to c17cc2027773e8e4913c5ab0fe3a489b1ed5bf81, 3267512ad1c2cc0c7768c5b014dc2cceb398a801 or 2855ddc6844f527e375e78afb55ec2a5182f23b3.

Affected software

Product	Affected	Fixed in
LinuxLinux	Affected ≥ 222993395ed38f3751287f4bd82ef46b3eb3a66d, < c17cc2027773e8e4913c5ab0fe3a489b1ed5bf81	Fixed in c17cc2027773e8e4913c5ab0fe3a489b1ed5bf81
LinuxLinux	Affected ≥ 222993395ed38f3751287f4bd82ef46b3eb3a66d, < 3267512ad1c2cc0c7768c5b014dc2cceb398a801	Fixed in 3267512ad1c2cc0c7768c5b014dc2cceb398a801
LinuxLinux	Affected ≥ 222993395ed38f3751287f4bd82ef46b3eb3a66d, < 2855ddc6844f527e375e78afb55ec2a5182f23b3	Fixed in 2855ddc6844f527e375e78afb55ec2a5182f23b3
LinuxLinux	Affected =5.7	Fixed in–

AI-suggested

A fix is available that keys FUT_OFF_MMSHARED futexes with a unique 64-bit per-MM ID to prevent wakeup misdirection. Users should apply the official Linux kernel update that includes this fix once released. No alternative mitigations or workarounds are indicated.

Description

A vulnerability in the Linux kernel futex subsystem involving FUT_OFF_MMSHARED futexes has been fixed. The issue allowed processes to wait on shared futexes referencing a freed memory management structure (MM), causing wakeups to be misdirected to new MMs at the same address. This was addressed by using a unique 64-bit per-MM ID to key FUT_OFF_MMSHARED futexes, preventing cross-MM wakeup consumption.

Impact

The vulnerability could cause futex waiters on a freed MM to incorrectly consume wakeups meant for a new MM at the same address, potentially leading to synchronization issues in multi-threaded processes. This could affect process coordination and stability but no direct exploitation or broader impact details are provided.

Summary

CVE-2026-99169 addresses a flaw in the Linux kernel futex implementation where FUT_OFF_MMSHARED futexes, which are shared futexes referring to an MM, could be misused due to improper handling of MM reuse. Specifically, a process could wait on a shared futex with a different MM because FUT_OFF_INODE waiters could be requeued onto FUT_OFF_MMSHARED futexes by other processes. This led to waiters on a freed MM consuming wakeups intended for a newly allocated MM at the same address. The fix introduced a unique 64-bit per-MM identifier to key FUT_OFF_MMSHARED futexes, ensuring correct wakeup delivery and maintaining performance by leaving private futexes unchanged.

References

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