CVE-2026-63802
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.
Affected versions
Linux kernel versions
6.3.9,
6.4
and later are affected. Fixed in
6.6.144,
6.12.95,
6.18.38,
7.1.3,
7.2-rc1
and their respective stable series.
References
5 totalFrequently asked questions
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What is CVE-2026-63802?
CVE-2026-63802 is a unscored severity Linux kernel vulnerability . It affects Linux kernel versions from 6.3.9 onward and has been patched in 6.6.144, 6.12.95, 6.18.38 and others. CVE-2026-63802 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.
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Is there a patch available for CVE-2026-63802?
Yes — CVE-2026-63802 has been patched. Fixed versions include 6.6.144, 6.12.95, 6.18.38 and others. If you are running Linux kernel 6.3.9 or later up to the fix versions, apply the relevant patch for your kernel branch.
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Is CVE-2026-63802 actively exploited?
No — CVE-2026-63802 has not been confirmed as actively exploited. It is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.