VulnerabilityPublished 25 Jul 2026Updated 30 Oct 2026

CVE-2026-64525: Linux kernel · xfrm: move policy_bydst RCU sync from per-netns .exit to .pre_exit

Affects Linux kernelSource CVE Database V5

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Not known to be exploited · fixed in d14ae8ef88c2c6590e107db61b6adce148cec7b3 : patch Linux kernel soon.

Data as of 30 Oct 2026, 13:33 UTC

Severity

High

Rated High by Threat Radar's AI analysis · No CVSS score from NVD or the CNA

Thin evidence

One scorer or none

Patch: Available – fixed in d14ae8ef88c2c6590e107db61b6adce148cec7b3, bca6386dc08750fc7cdcbc7683473748ba3114b9, 91cc13978ab0bc6f669139f53e7e613a860d10e0 +6

Exploitation evidence

Disclosed: evidence found.
CVE published 25 Jul 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 30 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade to a fixed release listed under Affected software.

Affected software

Product	Affected	Fixed in
LinuxLinux	Affected >=6.12.83 <6.12.93 >=6.18.24 <6.18.35 >=6.1.191 <6.2 >=6.6.136 <6.7 >=6.19.14 <6.20	Fixed in d14ae8ef88c2c6590e107db61b6adce148cec7b3 bca6386dc08750fc7cdcbc7683473748ba3114b9 91cc13978ab0bc6f669139f53e7e613a860d10e0 6.20 6.18.35 6.12.93 6.7 6.2 3e52417318473782012b236d0325bf7d2266a597
LinuxLinux	Affected =7.0	Fixed in–

AI-suggested

This vulnerability has been fixed in Linux kernel versions 6.2, 6.7, 6.12.93, 6.18.35, 6.20, and 7.0 as indicated by the fixed versions. Users and administrators should upgrade to these or later versions to resolve the issue. No additional mitigation actions are required beyond applying the official fix.

Description

A Linux kernel vulnerability related to improper handling of RCU synchronization in network namespace cleanup has been fixed. The issue involved blocking RCU primitives being called in the .exit handler instead of the recommended .pre_exit handler, causing excessive delays and resource accumulation during network namespace cleanup. This led to high memory usage and potential out-of-memory conditions on systems with many CPUs and frequent network namespace operations.

Impact

The vulnerability caused cleanup_net() and related kernel threads to become stuck in synchronize_rcu(), resulting in large accumulations of struct net objects in the cleanup queue and excessive memory consumption (over 130 GB on 256-CPU hosts). This could lead to memory control group (memcg) out-of-memory (OOM) conditions, impacting system stability and performance during heavy network namespace operations.

Summary

CVE-2026-64525 addresses a flaw in the Linux kernel's xfrm subsystem where the policy_bydst RCU synchronization was performed in the per-netns .exit handler rather than the documented .pre_exit handler. The violation caused cleanup_net() to perform multiple full RCU grace periods serially, leading to excessive delays and memory accumulation when cleaning up many network namespaces. The fix moves the policy flush and dependent workqueue drains to a new .pre_exit handler, ensuring O(1) RCU grace periods per batch instead of O(N), improving cleanup efficiency and preventing resource exhaustion. This issue was observed on Linux 6.18 under heavy network namespace creation and destruction workloads.

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 30 Oct 2026, 13:33 UTC

Technical details

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