CVE Catalog

CVE-2026-63802

HighCVSS 7.8
Published: Updated: Translated: NVD NIST

Exploitation Probability (EPSS)

Low risk
0.14%

4th percentile - higher than 4% of all known CVEs

Summary

A use-after-free vulnerability was found in the Linux kernel's __blkcg_rstat_flush() function in the blk-cgroup subsystem. It occurs when multiple blkgs in the same blkcg are released concurrently, causing a race condition and access to freed memory.

Risk Assessment

A local attacker could exploit this vulnerability to escalate privileges or cause a denial of service (DoS) by intentionally triggering the race condition during blkg release.

Recommendation

Immediately update the Linux kernel to a version containing the fix (commit moving flush from __blkg_release() to blkg_release()).

Other vulnerabilities in Linux kernel

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Original NVD description (English source)

In the Linux kernel, the following vulnerability has been resolved: blk-cgroup: fix UAF in __blkcg_rstat_flush() When multiple blkgs in the same blkcg are released concurrently, a use-after-free can occur. The race happens when one blkg's __blkcg_rstat_flush() removes another blkg's iostat entries via llist_del_all(). The second blkg sees an empty list and proceeds to free itself while the first is still iterating over its entries. Move the flush from __blkg_release() (RCU callback) to blkg_release() (before call_rcu). This ensures the RCU grace period waits for any concurrent flush's rcu_read_lock() section to complete before freeing.

Vulnerability data from NVD (NIST) · CISA KEV · EPSS