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Linux Kernel Futex Use-After-Free between Key Lookup and VMA Policy Scores 7.8

Last refreshed2026-09-26

Status: UPDATED  |  Advisory ID: CVE-2026-23415

Key Details

CVECVE-2026-23415
CVSS Score / Version7.8 (High) / CVSS v3.1
Updated2026-09-24
CVSS VectorCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
CVSS Proseattack vector is local; attack complexity is low; privileges required is low; user interaction is none; scope is unchanged; confidentiality impact is high; integrity impact is high; availability impact is high.
Affected productsLinux Linux Kernel
Classified asCWE-416 (Use After Free)
Exploitation prediction (EPSS)0.13% probability of exploitation in the next 30 days (2% percentile) -- FIRST.org's EPSS model.

Affected Products, Subsystems & Sectors

VendorProductAffected VersionsPatch Status
LinuxLinux Kernel
SubsystemsGeneral OT
SectorsAll Sectors

What to Know

In the Linux kernel, the following vulnerability has been resolved:

futex: Fix UaF between futex_key_to_node_opt() and vma_replace_policy()

During futex_key_to_node_opt() execution, vma->vm_policy is read under

speculative mmap lock and RCU. Concurrently, mbind() may call

vma_replace_policy() which frees the old mempolicy immediately via

kmem_cache_free().

This creates a race where __futex_key_to_node() dereferences a freed

mempolicy pointer, causing a use-after-free read of mpol->mode.

[ 151.412631] BUG: KASAN: slab-use-after-free in __futex_key_to_node (kernel/futex/core.c:349)

[ 151.414046] Read of size 2 at addr ffff888001c49634 by task e/87

[ 151.415969] Call Trace:

[ 151.416732] __asan_load2 (mm/kasan/generic.c:271)

[ 151.416777] __futex_key_to_node (kernel/futex/core.c:349)

[ 151.416822] get_futex_key (kernel/futex/core.c:374 kernel/futex/core.c:386 kernel/futex/core.c:593)

Fix by adding rcu to __mpol_put().

What to Do

Monitor Linux's web page for any future patch releases.

References

SourceReference
NVDhttps://nvd.nist.gov/vuln/detail/CVE-2026-23415
CVEhttps://www.cve.org/CVERecord?id=CVE-2026-23415