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CVE-2025-40348· NVD / CVE Program· CNA Linux

slab: Avoid race on slab->obj_exts in alloc_slab_obj_exts

In the Linux kernel, the following vulnerability has been resolved: slab: Avoid race on slab->obj_exts in alloc_slab_obj_exts If two competing threads enter alloc_slab_obj_exts() and one of them fails to allocate the object extension vector, it might override the valid slab->obj_exts allocated by the other thread with OBJEXTS_ALLOC_FAIL. This will cause the thread that lost this race and expects a valid pointer to dereference a NULL pointer later on. Update slab->obj_exts atomically using cmpxchg() to avoid slab->obj_exts overrides by racing threads. Thanks for Vlastimil and Suren's help with debugging.

—No exploit Fix available
Published
Dec 16, 2025
Updated
Jun 17, 2026
EPSS
0.2% · 8th percentile
CWE
—
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Action score

0

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Low priority for now.

CVSS
0 / 40 · —
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.2%

Affected systems

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Versions reported by the vendor

Affected version ranges reported by the assigning authority (Linux). Independent of NVD's CPE analysis and usually ahead of it.

  • Linux Linux

    • 715b6a5b41dae39baeaa40d3386b548bb278b9c2 and later · before c7af5300d78460fc5037ddc77113ba3dbfe77dc0affected · git
    • 07e38a54cabd9b4de7ceb7f075f29ffa463e458a and later · before 7c34feda6a9a203c9744281f1b6671b7dad2012daffected · git
    • f7381b9116407ba2a429977c80ff8df953ea9354 and later · before 6ed8bfd24ce1cb31742b09a3eb557cd008533eecaffected · git
    • 6.12.54 and later · before 6.12.56affected · semver
    • 6.17.4 and later · before 6.17.6affected · semver

Same product

linux: all records

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Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
Linux Linux6.12.56Vendor (CNA)
Linux Linux6.17.6Vendor (CNA)
Linux Linux6ed8bfd24ce1cb31742b09a3eb557cd008533eecVendor (CNA)
Linux Linux7c34feda6a9a203c9744281f1b6671b7dad2012dVendor (CNA)
Linux Linuxc7af5300d78460fc5037ddc77113ba3dbfe77dc0Vendor (CNA)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

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No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

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Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

No CVSS vector for this record, so attack conditions can't be derived.

Weakness class (CWE)

—

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Noroxi analysis

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Change log

  1. Fix✗ → ✓

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References

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

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