CVE-2025-40348

CVE-2025-40348 is a security vulnerability that is still awaiting full analysis and scoring. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low.

Key facts

Description

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.

Frequently asked questions

What is CVE-2025-40348?
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.
Is CVE-2025-40348 being actively exploited?
It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (6th percentile), an estimate of the probability of exploitation in the next 30 days.
How do I fix CVE-2025-40348?
Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2025-40348 have an EU (EUVD) identifier?
Yes. CVE-2025-40348 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-203639.
When was CVE-2025-40348 published?
CVE-2025-40348 was published on 2025-12-16 and last updated on 2026-06-17.

References