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Vulnerability · CVE-2026-43439

In the Linux kernel, the following vulnerability has been resolved: cgroup: fix race between task migration and iteration When a task is migrated out of a css_set, cgr…

Published May 8, 2026 · corrected/updated Jun 17, 2026 · linux linux kernel · evidence confidence high

In the Linux kernel, the following vulnerability has been resolved: cgroup: fix race between task migration and iteration When a task is migrated out of a css_set, cgroup_migrate_add_task() first moves it from cset->tasks to cset->mg_tasks via: list_move_tail(&task->cg_list, &cset->mg_tasks); If a css_task_iter currently has it->task_pos pointing to this task, css_set_move_task() calls css_task_iter_skip() to keep the iterator valid. However, since the task has already been moved to ->mg_tasks, the iterator is advanced relative to the mg_tasks list instead of the original tasks list. As a result, remaining tasks on cset->tasks, as well as tasks queued on cset->mg_tasks, can be skipped by iteration. Fix this by calling css_set_skip_task_iters() before unlinking task->cg_list from cset->tasks. This advances all active iterators to the next task on cset->tasks, so iteration continues correctly even when a task is concurrently being migrated. This race is hard to hit in practice without instrumentation, but it can be reproduced by artificially slowing down cgroup_procs_show(). For example, on an Android device a temporary /sys/kernel/cgroup/cgroup_test knob can be added to inject a delay into cgroup_procs_show(), and then: 1) Spawn three long-running tasks (PIDs 101, 102, 103). 2) Create a test cgroup and move the tasks into it. 3) Enable a large delay via /sys/kernel/cgroup/cgroup_test. 4) In one shell, read cgroup.procs from the test cgroup. 5) Within the delay window, in another shell migrate PID 102 by writing it to a different cgroup.procs file. Under this setup, cgroup.procs can intermittently show only PID 101 while skipping PID 103. Once the migration completes, reading the file again shows all tasks as expected. Note that this change does not allow removing the existing css_set_skip_task_iters() call in css_set_move_task(). The new call in cgroup_migrate_add_task() only handles iterators that are racing with migration while the task is still on cset->tasks. Ite

Grounded briefings

Catalog interpretations for three audiences. Each brief cites ingested metadata and the original advisories below. They are not independent research and they do not invent exploit steps.

Executive

CVE-2026-43439 is a medium public vulnerability record for linux linux kernel. It is not currently listed in the CISA Known Exploited catalog. Check the linked vendor or CERT advisories for patch status. This summary is a catalog interpretation of the ingested metadata and cites the original advisories below.

System administrator

Identify whether linux linux kernel is in your estate, then compare installed versions with the affected ranges. Affected packages or ranges on record: linux/linux kernel. Check the linked vendor or CERT advisories for patch status. Prefer the vendor or distribution advisory linked in Sources before changing production systems. This is a catalog interpretation, not a runbook.

Security analyst

Signals on file: CVSS 4.7, EPSS 0.1%. It is not currently listed in the CISA Known Exploited catalog. Weakness classes: CWE-362. Sources contributing to this record: cve_org, epss, nvd. Public exploit references, when present, are outbound links only and are not proof of active exploitation. This is a catalog interpretation of stored metadata.

Exploitation and remediation

  • Exploitation evidence

    Not listed as known exploited in CISA KEV. Not in CISA KEV or VulnCheck KEV.

  • Patch and remediation

    No required-action text is stored yet. Use the vendor or CERT links in Sources for patch availability.

  • Safe detection guidance

    Compare installed versions with the affected ranges below and verify the advisory from the original publisher. This site stores metadata and outbound links only; it does not ship exploit code or proof-of-concept payloads.

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. May 8, 2026 · NIST NVD

    Detected

    In the Linux kernel, the following vulnerability has been resolved: cgroup: fix race between task migration and iteration When a task is migrated out of a css_set, cgroup_migrate_add_task() first moves it from cset->tasks to cset->mg_tasks via: list_move_tail(&task->cg_list, &cset->mg_tasks); If a css_task_iter currently has it->task_pos pointing to this task, css_set_move_task() calls css_task_it

  2. Jun 17, 2026 · NIST NVD

    Updated

    In the Linux kernel, the following vulnerability has been resolved: cgroup: fix race between task migration and iteration When a task is migrated out of a css_set, cgroup_migrate_add_task() first moves it from cset->tasks to cset->mg_tasks via: list_move_tail(&task->cg_list, &cset->mg_tasks); If a css_task_iter currently has it->task_pos pointing to this task, css_set_move_task() calls css_task_it

Affected

  • cpe linux/linux kernelversion unspecified

Sources

  • CVE.orgVulnerability recordCVE-2026-43439

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2026-43439

    30-day exploitation probability 0.1%

    first.org
  • NIST NVDVulnerability recordCVE-2026-43439

    In the Linux kernel, the following vulnerability has been resolved: cgroup: fix race between task migration and iteration When a task is migrated out of a css_set, cgroup_migrate_add_task() first moves it from cset->tasks to cset->mg_tasks via: list_move_tail(&task->cg_lis

    nvd.nist.gov

References