VulnerabilityPublished 8 May 2026

CVE-2026-43418: Linux kernel · sched/mmcid: Prevent CID stalls due to concurrent forks

Source GCVE Database

Not known to be exploited.

Data as of 27 Oct 2026, 03:19 UTC

Severity

High

Rated High by Threat Radar's AI analysis · No CVSS score from NVD or the CNA

Exploitation evidence

Disclosed: evidence found.
CVE published 8 May 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-5r8w-mfmh-79h7

What to do

AI-suggested

A fix has been implemented that reorders the sched_mm_cid_fork() call to after the new task becomes visible in the thread and task lists. Users should apply the official Linux kernel patches that address this issue once available. Until patched, systems may be at risk of stalls under concurrent fork conditions.

Description

A concurrency issue in the Linux kernel's sched/mmcid subsystem could cause CPU stalls due to improper handling of concurrent forks. The flaw occurs because a newly forked task is accounted as an MMCID user before it becomes visible in the process and global task lists, leading to missed fixups of allocated CIDs and potential machine stalls. The fix moves the accounting call to after the task becomes visible, aligning it with task exit behavior.

References

Community reviews

Loading reviews…