CVE-2026-43417

5.5 MEDIUM 0.1% exploit odds Fix listed Other OS & kernel

What it is

In the Linux kernel, the following vulnerability has been resolved: sched/mmcid: Handle vfork()/CLONE_VM correctly Matthieu and Jiri reported stalls where a task endlessly loops in mm_get_cid() when scheduling in. It turned out that the logic which handles vfork()'ed tasks is broken. It is invoked when the number of tasks associated to a process is smaller than the number of MMCID users. It then walks the task list to find the vfork()'ed task, but accounts all the already processed tasks as well. If that double processing brings the number of to be handled tasks to 0, the walk stops and the vfork()'ed task's CID is not fixed up. As a consequence a subsequent schedule in fails to acquire a (transitional) CID and the machine stalls. Cure this by removing the accounting condition and make the fixup always walk the full task list if it could not find the exact number of users in the process' thread list.

At a glance

Exploitability: Can be exploited locally on the machine with a low-privilege account. High risk of service disruption.
Exploit odds: 0.1% chance of exploitation in the next 30 days (EPSS).
Fix: A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

2026-05-08 15:16 UTC PublishedDisclosed publicly on CVE.org and NVD
2026-06-17 10:49 UTC Last updatedMost recent change to the record

Why it ranks here

Exploited in the wild: no, CISA does not list it.
Exploit odds: 0.1% in the next 30 days (EPSS).
Severity: 5.5 MEDIUM (CVSS).
Fix: a patch or advisory is linked.

Details

Published: 2026-05-08 15:16 UTC
Last modified: 2026-06-17 10:49 UTC
Exploit probability: 0.1% · EPSS, next 30 days
Record status: Analyzed

Affected

Linux Kernel < 6.19.9
Linux Kernel 7.0

Attack profile CVSS 3.1 · 5.5

Attack vector: Local
Complexity: Low
Privileges needed: Low
User interaction: None
Scope: Unchanged
Confidentiality: None
Integrity: None
Availability: High

Raw vector

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Is it in your code?

Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.

Read https://cve-list.com/agent/cve/CVE-2026-43417.md and follow it. Check whether this project is affected by CVE-2026-43417. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

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Fix and advisories

References

NVD record · CVE.org record