CVE-2026-43418
In the Linux kernel, the following vulnerability has been resolved:
sched/mmcid: Prevent CID stalls due to concurrent forks
A newly forked task is accounted as MMCID user before the task is visible in the process' thread list and the global task list. This creates the following problem:
CPU1 CPU2 fork() sched_mm_cid_fork(tnew1) tnew1->mm.mm_cid_users++; tnew1->mm_cid.cid = getcid() -> preemption fork() sched_mm_cid_fork(tnew2) tnew2->mm.mm_cid_users++; // Reaches the per CPU threshold mm_cid_fixup_tasks_to_cpus() for_each_other(current, p) ....
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As tnew1 is not visible yet, this fails to fix up the already allocated CID of tnew1. As a consequence a subsequent schedule in might fail to acquire a (transitional) CID and the machine stalls.
Move the invocation of sched_mm_cid_fork() after the new task becomes visible in the thread and the task list to prevent this.
This also makes it symmetrical vs. exit() where the task is removed as CID user before the task is removed from the thread and task lists.
CVSS
- Versión: 3.1
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
- Puntuación base: 5.5
Probabilidad de explotación (EPSS)
- Probabilidad de explotación en los próximos 30 días: 0.14%
- Percentil entre todas las CVEs puntuadas: 3
- Fecha de la puntuación: 6/10/2026
EPSS (Exploit Prediction Scoring System, de FIRST) estima la probabilidad de que una vulnerabilidad sea explotada en 30 días. Complementa a CVSS (impacto) y a CISA KEV (explotación confirmada).
Tecnologías afectadas (1)
CWE
- NVD-CWE-noinfo
Referencias
JSON original (NVD)
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"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nsched/mmcid: Prevent CID stalls due to concurrent forks\n\nA newly forked task is accounted as MMCID user before the task is visible\nin the process' thread list and the global task list. This creates the\nfollowing problem:\n\n CPU1\t\t\tCPU2\n fork()\n sched_mm_cid_fork(tnew1)\n tnew1->mm.mm_cid_users++;\n tnew1->mm_cid.cid = getcid()\n-> preemption\n\t\t\tfork()\n\t\t\t sched_mm_cid_fork(tnew2)\n\t\t\t tnew2->mm.mm_cid_users++;\n // Reaches the per CPU threshold\n\t\t\t mm_cid_fixup_tasks_to_cpus()\n\t\t\t for_each_other(current, p)\n\t\t\t ....\n\nAs tnew1 is not visible yet, this fails to fix up the already allocated CID\nof tnew1. As a consequence a subsequent schedule in might fail to acquire a\n(transitional) CID and the machine stalls.\n\nMove the invocation of sched_mm_cid_fork() after the new task becomes\nvisible in the thread and the task list to prevent this.\n\nThis also makes it symmetrical vs. exit() where the task is removed as CID\nuser before the task is removed from the thread and task lists."
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"lastModified": "2026-06-17T10:49:33.627",
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