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Vulnerability · Published Dec 16, 2025 · Assigned by Linux

CVE-2025-40348slab: Avoid race on slab->obj_exts in alloc_slab_obj_exts

Unrated

In plain English

A security flaw in Linux from Linux. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 10% of all known vulnerabilities).

Severity (CVSS )–Not rated
Exploit odds (30 days)0.2%top 90.2% of all CVEs
Exploited in the wildNo reportsnot in CISA KEV
Attack toolingNoneno public tooling known

Official 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.

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
Ubuntu:22.04:LTSlinux-allwinner-5.19no fix listedUBUNTU-CVE-2025-40348
Ubuntu:22.04:LTSlinux-aws-5.19no fix listedUBUNTU-CVE-2025-40348
Ubuntu:22.04:LTSlinux-aws-6.2no fix listedUBUNTU-CVE-2025-40348
Ubuntu:22.04:LTSlinux-aws-6.5no fix listedUBUNTU-CVE-2025-40348
Ubuntu:22.04:LTSlinux-azure-5.19no fix listedUBUNTU-CVE-2025-40348
Ubuntu:24.04:LTSlinux-azure-6.11no fix listedUBUNTU-CVE-2025-40348
Ubuntu:22.04:LTSlinux-azure-6.2no fix listedUBUNTU-CVE-2025-40348
Ubuntu:22.04:LTSlinux-azure-6.5no fix listedUBUNTU-CVE-2025-40348
Ubuntu:22.04:LTSlinux-azure-fde-5.19no fix listedUBUNTU-CVE-2025-40348
Ubuntu:22.04:LTSlinux-azure-fde-6.2no fix listedUBUNTU-CVE-2025-40348
Ubuntu:22.04:LTSlinux-gcp-5.19no fix listedUBUNTU-CVE-2025-40348
Ubuntu:24.04:LTSlinux-gcp-6.11no fix listedUBUNTU-CVE-2025-40348
Ubuntu:22.04:LTSlinux-gcp-6.2no fix listedUBUNTU-CVE-2025-40348
Ubuntu:22.04:LTSlinux-gcp-6.5no fix listedUBUNTU-CVE-2025-40348
Ubuntu:22.04:LTSlinux-hwe-5.19no fix listedUBUNTU-CVE-2025-40348
Ubuntu:24.04:LTSlinux-hwe-6.11no fix listedUBUNTU-CVE-2025-40348
Ubuntu:22.04:LTSlinux-hwe-6.2no fix listedUBUNTU-CVE-2025-40348
Ubuntu:22.04:LTSlinux-hwe-6.5no fix listedUBUNTU-CVE-2025-40348
Ubuntu:22.04:LTSlinux-intel-iot-realtimeno fix listedUBUNTU-CVE-2025-40348
Ubuntu:22.04:LTSlinux-lowlatency-hwe-5.19no fix listedUBUNTU-CVE-2025-40348
Ubuntu:24.04:LTSlinux-lowlatency-hwe-6.11no fix listedUBUNTU-CVE-2025-40348
Ubuntu:22.04:LTSlinux-lowlatency-hwe-6.2no fix listedUBUNTU-CVE-2025-40348
Ubuntu:22.04:LTSlinux-lowlatency-hwe-6.5no fix listedUBUNTU-CVE-2025-40348
Ubuntu:24.04:LTSlinux-nvidia-6.11no fix listedUBUNTU-CVE-2025-40348
Ubuntu:22.04:LTSlinux-nvidia-6.2no fix listedUBUNTU-CVE-2025-40348
Ubuntu:22.04:LTSlinux-nvidia-6.5no fix listedUBUNTU-CVE-2025-40348
Ubuntu:22.04:LTSlinux-oem-5.17no fix listedUBUNTU-CVE-2025-40348
Ubuntu:22.04:LTSlinux-oem-6.0no fix listedUBUNTU-CVE-2025-40348
Ubuntu:22.04:LTSlinux-oem-6.1no fix listedUBUNTU-CVE-2025-40348
Ubuntu:24.04:LTSlinux-oem-6.11no fix listedUBUNTU-CVE-2025-40348
Ubuntu:22.04:LTSlinux-oem-6.5no fix listedUBUNTU-CVE-2025-40348
Ubuntu:24.04:LTSlinux-oem-6.8no fix listedUBUNTU-CVE-2025-40348
Ubuntu:22.04:LTSlinux-oracle-6.5no fix listedUBUNTU-CVE-2025-40348
Ubuntu:24.04:LTSlinux-raspi-realtimeno fix listedUBUNTU-CVE-2025-40348
Ubuntu:22.04:LTSlinux-realtimeno fix listedUBUNTU-CVE-2025-40348
Ubuntu:24.04:LTSlinux-realtimeno fix listedUBUNTU-CVE-2025-40348
Ubuntu:22.04:LTSlinux-riscvno fix listedUBUNTU-CVE-2025-40348
Ubuntu:24.04:LTSlinux-riscvno fix listedUBUNTU-CVE-2025-40348
Ubuntu:22.04:LTSlinux-riscv-5.19no fix listedUBUNTU-CVE-2025-40348
Ubuntu:24.04:LTSlinux-riscv-6.14no fix listedUBUNTU-CVE-2025-40348
Ubuntu:22.04:LTSlinux-riscv-6.5no fix listedUBUNTU-CVE-2025-40348
Ubuntu:22.04:LTSlinux-starfive-5.19no fix listedUBUNTU-CVE-2025-40348
Ubuntu:22.04:LTSlinux-starfive-6.2no fix listedUBUNTU-CVE-2025-40348
Ubuntu:22.04:LTSlinux-starfive-6.5no fix listedUBUNTU-CVE-2025-40348

Affected products (as reported)

VendorProductVersions
Linux Linux 715b6a5b41dae39baeaa40d3386b548bb278b9c2 – before c7af5300d78460fc5037ddc77113ba3dbfe77dc007e38a54cabd9b4de7ceb7f075f29ffa463e458a – before 7c34feda6a9a203c9744281f1b6671b7dad2012df7381b9116407ba2a429977c80ff8df953ea9354 – before 6ed8bfd24ce1cb31742b09a3eb557cd008533eec
Linux Linux 6.12.54 – before 6.12.566.17.4 – before 6.17.6

References