CVE-2026-53239
Received Received - Intake
Use-After-Free in Linux Kernel XFRM Policy

Publication date: 2026-06-25

Last updated on: 2026-06-25

Assigner: kernel.org

Description
In the Linux kernel, the following vulnerability has been resolved: xfrm: policy: fix use-after-free on inexact bin in xfrm_policy_bysel_ctx() Fix the race by pruning the bin while still holding xfrm_policy_lock, before dropping it. Use __xfrm_policy_inexact_prune_bin() directly since the lock is already held. The wrapper xfrm_policy_inexact_prune_bin() becomes unused and is removed. Race: CPU0 (XFRM_MSG_DELPOLICY) CPU1 (XFRM_MSG_NEWSPDINFO) ========================== ========================== xfrm_policy_bysel_ctx(): spin_lock_bh(xfrm_policy_lock) bin = xfrm_policy_inexact_lookup() __xfrm_policy_unlink(pol) spin_unlock_bh(xfrm_policy_lock) xfrm_policy_kill(ret) // wide window, lock not held xfrm_hash_rebuild(): spin_lock_bh(xfrm_policy_lock) __xfrm_policy_inexact_flush(): kfree_rcu(bin) // bin freed spin_unlock_bh(xfrm_policy_lock) xfrm_policy_inexact_prune_bin(bin) // UAF: bin is freed
CVSS Scores
EPSS Scores
Probability:
Percentile:
Meta Information
Published
2026-06-25
Last Modified
2026-06-25
Generated
2026-06-25
AI Q&A
2026-06-25
EPSS Evaluated
N/A
NVD
CVE-2026-53239
EUVD
EUVD-2026-39330
Affected Vendors & Products
Showing 1 associated CPE
Vendor Product Version / Range
linux linux_kernel *
Helpful Resources
Exploitability
CWE
CWE Icon
KEV
KEV Icon
CWE ID Description
CWE-UNKNOWN
Attack-Flow Graph
AI Quick Actions
Instant insights powered by AI
Executive Summary

This vulnerability is a use-after-free (UAF) issue in the Linux kernel's xfrm policy code, specifically in the function xfrm_policy_bysel_ctx().

The problem arises due to a race condition between two CPUs: one executing a policy deletion (XFRM_MSG_DELPOLICY) and the other rebuilding the policy hash (XFRM_MSG_NEWSPDINFO).

During this race, a data structure called 'bin' is freed by one CPU while the other CPU still tries to access it, leading to a use-after-free error.

The fix involves pruning the 'bin' while still holding the xfrm_policy_lock to prevent the race, and removing an unused wrapper function.

Impact Analysis

A use-after-free vulnerability in the Linux kernel can lead to undefined behavior, including system crashes, memory corruption, or potential escalation of privileges.

Exploitation of this vulnerability could allow an attacker to execute arbitrary code in kernel context or cause denial of service by crashing the system.

Chat Assistant
Ask questions about this CVE
Hi! I’m here to help you understand CVE-2026-53239. Ask me anything about the vulnerability, its impact, or mitigation strategies.
0/70
EPSS Chart