Vulnerability Description
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.
CVSS Score
HIGH
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Linux | Linux Kernel | >= 6.3.9, < 6.4 |
Related Weaknesses (CWE)
References
- https://git.kernel.org/stable/c/0ab5ee5a1badb58cbb2242617cb01a4972b1f2a2Patch
- https://git.kernel.org/stable/c/5e5b7f2ef854936e95dceb6a2fdfefcb7152d2c6Patch
- https://git.kernel.org/stable/c/96e545410c4f74c89d496c1d5d9ef8d08f14368bPatch
- https://git.kernel.org/stable/c/afebe44facc48a61761e885bbb7f0380d4a603ecPatch
- https://git.kernel.org/stable/c/bbebd9425cad3573d1527441753899b926525a0fPatch
FAQ
What is CVE-2026-63802?
CVE-2026-63802 is a vulnerability with a CVSS score of 7.8 (HIGH). 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...
How severe is CVE-2026-63802?
CVE-2026-63802 has been rated HIGH with a CVSS base score of 7.8/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2026-63802?
Check the references section above for vendor advisories and patch information. Affected products include: Linux Linux Kernel.