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VulnerabilityPublished Updated

CVE-2026-52973: Linux kernel · futex: Drop CLONE_THREAD requirement for private default hash alloc

Affects Linux kernelSource CVE Database V5

0

Not known to be exploited · CVSS 7.8 High · fixed in ee9dce44362b2d8132c32964656ab6dff7dfbc6a : patch Linux kernel soon.

Data as of 26 Oct 2026, 13:47 UTC

CVSS 3.1 base score
7.8High
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.1% chance of exploitation in 30 days – higher than 7% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
CISA SSVC
Exploitation
No evidence of active exploitation and no public proof of concept
Automatable
Attackers cannot reliably automate steps 1–4 of the kill chain
Technical impact
Total control over the software or total information disclosure

CISA SSVC assessment, 2026-10-16.

Patch
Available – fixed in ee9dce44362b2d8132c32964656ab6dff7dfbc6a, 974ac49a9a068b0591a59f65c63eb06579a13091, 1dcd36420af2da5bd59306dba9caf78e3d248b1d
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 24 Jun 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

What to do

Upgrade Linux kernel to ee9dce44362b2d8132c32964656ab6dff7dfbc6a, 974ac49a9a068b0591a59f65c63eb06579a13091 or 1dcd36420af2da5bd59306dba9caf78e3d248b1d.

Affected software

ProductAffectedFixed in
LinuxLinuxAffected
  • ≥ d9b05321e21e4b218de4ce8a590bf375f58b6346, < ee9dce44362b2d8132c32964656ab6dff7dfbc6a
Fixed in
  • ee9dce44362b2d8132c32964656ab6dff7dfbc6a
LinuxLinuxAffected
  • ≥ d9b05321e21e4b218de4ce8a590bf375f58b6346, < 974ac49a9a068b0591a59f65c63eb06579a13091
Fixed in
  • 974ac49a9a068b0591a59f65c63eb06579a13091
LinuxLinuxAffected
  • ≥ d9b05321e21e4b218de4ce8a590bf375f58b6346, < 1dcd36420af2da5bd59306dba9caf78e3d248b1d
Fixed in
  • 1dcd36420af2da5bd59306dba9caf78e3d248b1d
LinuxLinuxAffected
  • =6.17
Fixed in–

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.

References

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