Use After Free Affecting kernel-rt-debug-core package, versions <0:4.18.0-553.163.1.rt7.504.el8_10


Severity

Recommended
high

Based on AlmaLinux security rating.

Threat Intelligence

EPSS
0.13% (3rd percentile)

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  • Snyk IDSNYK-ALMALINUX8-KERNELRTDEBUGCORE-19852573
  • published16 Sept 2026
  • disclosed15 Sept 2026

Introduced: 15 Sep 2026

NewCVE-2026-63802  (opens in a new tab)
CWE-416  (opens in a new tab)

How to fix?

Upgrade AlmaLinux:8 kernel-rt-debug-core to version 0:4.18.0-553.163.1.rt7.504.el8_10 or higher.
This issue was patched in ALSA-2026:67469.

NVD Description

Note: Versions mentioned in the description apply only to the upstream kernel-rt-debug-core package and not the kernel-rt-debug-core package as distributed by AlmaLinux. See How to fix? for AlmaLinux:8 relevant fixed versions and status.

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 Base Scores

version 3.1