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Linux KernelOperating system · Linux

CVE-2026-52973

HIGH · 7.8 CVSS v3.1 Published 2026-06-24
Fix available
A fix is available. Upgrade to 6.18.33 / 7.0.10 or later.
See remediation →
80/100
Remediation priority · High
Zero-click 8 weeks old

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
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.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

Linux kernel futex implementation vulnerability where need_futex_hash_allocate_default() incorrectly depends on CLONE_THREAD rather than CLONE_VM, causing a use-after-free (KASAN: slab-use-after-free in futex_hash_put). The +1 bias can end up on a percpu counter that mm->futex_ref no longer points at when mm is shared via CLONE_VM without CLONE_THREAD.

MitigationApply the upstream kernel patch that changes the check from CLONE_THREAD to any CLONE_VM clone (excluding vfork), recompile and deploy the patched kernel.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Linux KernelOperating system
Affected:>= 6.17.1, < 6.18.33>= 6.19, < 7.0.10= 6.17= 7.1

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Local
Complexity
Low
Privileges
Low
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

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

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Check kernel version
    Run `uname -r` or `cat /proc/version` to get the running kernel version
    Affected if The kernel version falls within these ranges: >= 6.17.1 and < 6.18.33; >= 6.19 and < 7.0.10; equals 6.17; or equals 7.1
  2. Verify futex is available
    Check for existence of `/proc/sys/fs/futex/` or run `grep -i futex /proc/mounts`
    Affected if Futex filesystem or sysfs entries exist (futex is active in the kernel)
  3. Check for processes using unusual clone flags
    Monitor for processes created with CLONE_VM (0x200) but without CLONE_THREAD (0x20000) - this typically requires tracing tools like `strace -f` or `perf` to observe clone() syscalls
    Affected if Any process on the system uses clone() with CLONE_VM without CLONE_THREAD flag (rare, but possible with certain custom threading libraries or container runtimes)

The system is affected if the running kernel version is in the affected ranges AND processes using CLONE_VM without CLONE_THREAD are present, leading to potential use-after-free in futex_hash_put operations.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 6.18.33 / 7.0.10 or later
Fixed in 6.18.337.0.10
Interim mitigation

Apply the upstream kernel patch that changes the check from CLONE_THREAD to any CLONE_VM clone (excluding vfork), recompile and deploy the patched kernel.

Recommended fix High confidence

Linux Kernel 6.18.33 or later, or 7.0.10 or later (depending on which major version branch you are on)

  1. Identify the currently running Linux kernel version using `uname -r`
  2. If running kernel version >= 6.17.1 and < 6.18.33, upgrade to kernel version 6.18.33 or later
  3. If running kernel version >= 6.19 and < 7.0.10, upgrade to kernel version 7.0.10 or later
  4. If running kernel version 6.17.x (where x < 1), upgrade to 6.18.33 or later
  5. If running kernel version 7.1, upgrade to 7.0.10 or later
  6. After kernel upgrade, reboot the system to load the fixed kernel
  7. Verify the fix by checking that the futex_hash_put use-after-free no longer occurs under the previously triggering conditions (sharing mm via CLONE_VM without CLONE_THREAD)
Caveat Kernel upgrades may require system downtime and should be tested in a staging environment first; ensure compatibility with existing system software and drivers

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Linux Kernel Scoped from the published advisory
  • Consultation4.0 h
  • Implementation2.0 h
  • Testing8.0 h
  • Review / QA4.0 h
18.0 hours of engineering $3,080
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-52973 in production — separate from our analysis above.

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
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