CVE-2026-43417 (GCVE-0-2026-43417)

Vulnerability from cvelistv5 – Published: 2026-05-08 14:21 – Updated: 2026-05-11 22:24
VLAI
Title
sched/mmcid: Handle vfork()/CLONE_VM correctly
Summary
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.
Severity
5.5 (Medium)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: fbd0e71dc370af73f6b316e4de9eed273dd90340 , < e6761cdce78a8919a537989afb6aaf6881469f83 (git)
Affected: fbd0e71dc370af73f6b316e4de9eed273dd90340 , < 28b5a1395036d6c7a6c8034d85ad3d7d365f192c (git)
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Linux Linux Affected: 6.19
Unaffected: 0 , < 6.19 (semver)
Unaffected: 6.19.9 , ≤ 6.19.* (semver)
Unaffected: 7.0 , ≤ * (original_commit_for_fix)
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    "redhat_vex": {
      "aggregate_severity": "None",
      "current_release_date": "2026-06-28T11:29:08+00:00",
      "cve": "CVE-2026-43417",
      "id": "CVE-2026-43417",
      "initial_release_date": "2026-05-08T00:00:00+00:00",
      "product_status:known_not_affected": "274",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: sched/mmcid: Handle vfork()/CLONE_VM correctly",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-43417.json",
      "version": "3"
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}



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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

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Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


Detection rules are retrieved from Rulezet.