Riskcovery

CVE-2026-52973

futex: Drop CLONE_THREAD requirement for private default hash alloc

State
Published
Severity
7.8 High
Published
Jun 24, 2026
Updated
Oct 19, 2026
Reserved
Jun 9, 2026

Read the record on cve.org

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.

Scores

CVSSScoreVectorSource
3.17.8 HighCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:HLinux
3.17.0 HighCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:Hredhat-SADP

Weaknesses

  • CWE-825 Expired Pointer Dereference

Affected Products

ProductVersions
LinuxLinux
  • d9b05321e21e4b218de4ce8a590bf375f58b6346 to before 1dcd36420af2da5bd59306dba9caf78e3d248b1dAffected
  • d9b05321e21e4b218de4ce8a590bf375f58b6346 to before 974ac49a9a068b0591a59f65c63eb06579a13091Affected
  • d9b05321e21e4b218de4ce8a590bf375f58b6346 to before ee9dce44362b2d8132c32964656ab6dff7dfbc6aAffected
LinuxLinux
  • 6.17Affected
  • before 6.17Not affected
  • 6.18.33 through 6.18.*Not affected
  • 7.0.10 through 7.0.*Not affected
  • 7.1 and laterNot affected

References

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