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Vulnerability record · CVE-2026-52973 · published 24 June 2026

CVE-2026-52973: Linux kernel use after free vulnerability

Linux · Linux Kernel

In the Linux kernel, the following vulnerability has been resolved: futex: Drop CLONE_THREAD requirement for private default hash alloc Currently need_futex_hash_allocate_default() depends on strict pthread semantics, abusing CLONE_THREAD. This breaks the non-concurrency assumptions when doing the mm->futex_ref pcpu allocations, leading to bugs[0] when sharing the mm in other ways; ie: BUG: KASAN: slab-use-after-free in futex_hash_put ... where the +1 bias can end up on a percpu counter that mm->futex_ref no longer points at. Loosen the check to cover any CLONE_VM clone, except vfork(). Excluding vfork keeps the existing paths untouched (no overhead), and we can't race in the first place: either the parent is suspended and the child runs alone, or mm->futex_ref is already allocated from an earlier CLONE_VM.

7.8 CVSS 3.1 High EPSS 0.18% · top 92.8% CWE-416 · Use after freeCWE-825 · CWE-825
7.8CVSS 3.1 base score
0.18%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
10References
3 Sep 2026Last modified by NVD

Description

In the Linux kernel, the following vulnerability has been resolved: futex: Drop CLONE_THREAD requirement for private default hash alloc Currently need_futex_hash_allocate_default() depends on strict pthread semantics, abusing CLONE_THREAD. This breaks the non-concurrency assumptions when doing the mm->futex_ref pcpu allocations, leading to bugs[0] when sharing the mm in other ways; ie: BUG: KASAN: slab-use-after-free in futex_hash_put ... where the +1 bias can end up on a percpu counter that mm->futex_ref no longer points at. Loosen the check to cover any CLONE_VM clone, except vfork(). Excluding vfork keeps the existing paths untouched (no overhead), and we can't race in the first place: either the parent is suspended and the child runs alone, or mm->futex_ref is already allocated from an earlier CLONE_VM.

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

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://git.kernel.org/stable/c/1dcd36420af2da5bd59306dba9caf78e3d248b1d Patch
https://git.kernel.org/stable/c/974ac49a9a068b0591a59f65c63eb06579a13091 Patch
https://git.kernel.org/stable/c/ee9dce44362b2d8132c32964656ab6dff7dfbc6a Patch
https://access.redhat.com/errata/RHSA-2026:45114
https://access.redhat.com/errata/RHSA-2026:47040
https://access.redhat.com/errata/RHSA-2026:62640
https://access.redhat.com/errata/RHSA-2026:62642
https://access.redhat.com/security/cve/CVE-2026-52973 Third Party Advisory
https://bugzilla.redhat.com/show_bug.cgi?id=2492413 Issue TrackingThird Party Advisory
https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-52973.json Third Party Advisory

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Source: NIST National Vulnerability Database (record CVE-2026-52973), CISA KEV, FIRST EPSS (scores of 2026-09-27). This page is refreshed as NVD updates the record.