CVE-2026-64525 Affecting kernel-azure-extra package, versions <6.12.0-160000.38.1
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Test your applications- Snyk IDSNYK-SLES1600-KERNELAZUREEXTRA-20319668
- published30 Sept 2026
- disclosed22 Sept 2026
Introduced: 22 Sep 2026
NewCVE-2026-64525 (opens in a new tab)How to fix?
Upgrade SLES:16.0.0 kernel-azure-extra to version 6.12.0-160000.38.1 or higher.
NVD Description
Note: Versions mentioned in the description apply only to the upstream kernel-azure-extra package and not the kernel-azure-extra package as distributed by SLES.
See How to fix? for SLES:16.0.0 relevant fixed versions and status.
In the Linux kernel, the following vulnerability has been resolved:
xfrm: move policy_bydst RCU sync from per-netns .exit to .pre_exit
The struct pernet_operations docstring in include/net/net_namespace.h explicitly warns against blocking RCU primitives in .exit handlers:
Exit methods using blocking RCU primitives, such as synchronize_rcu(), should be implemented via exit_batch. [...] Please, avoid synchronize_rcu() at all, where it's possible.
Note that a combination of pre_exit() and exit() can be used, since a synchronize_rcu() is guaranteed between the calls.
xfrm_policy_fini() violates this: it calls synchronize_rcu() before freeing the policy_bydst hash tables (so no RCU reader is mid- traversal at free time), but runs from xfrm_net_ops.exit -- once per namespace -- so a cleanup_net() of N namespaces pays N full RCU grace periods serially.
Use the documented pre_exit/exit split. Move the policy flush (and the workqueue drains it depends on) into a new .pre_exit handler; xfrm_policy_fini() then runs in .exit and frees the hash tables after the synchronize_rcu_expedited() that cleanup_net() guarantees between the two phases. Providing O(1) RCU grace periods per batch instead of O(N).
Observed on Linux 6.18 with a workload doing unshare(CLONE_NEWNET) at ~13/sec sustained: cleanup_net() and the netns_wq rescuer kthread both stuck in xfrm_policy_fini()'s synchronize_rcu(), >300k struct net accumulated in the cleanup queue, Percpu in /proc/meminfo climbed to 130+ GB on 256-CPU hosts, and memcg OOMs followed. setup_net and __put_net counts were balanced, ruling out a refcount leak.
References
- https://www.suse.com/security/cve/CVE-2026-64525.html
- https://bugzilla.suse.com/1274292
- https://git.kernel.org/stable/c/3e52417318473782012b236d0325bf7d2266a597
- https://git.kernel.org/stable/c/91cc13978ab0bc6f669139f53e7e613a860d10e0
- https://git.kernel.org/stable/c/bca6386dc08750fc7cdcbc7683473748ba3114b9
- https://git.kernel.org/stable/c/d14ae8ef88c2c6590e107db61b6adce148cec7b3