SB2026072133 - Use-after-free in Linux kernel block
Published: July 21, 2026
Security Bulletin ID
SB2026072133
CSH Severity
Low
Patch available
YES
Number of vulnerabilities
1
Exploitation vector
Local access
Highest impact
Denial of service
Breakdown by Severity
- Low
- Medium
- High
- Critical
Description
This security bulletin contains information about 1 vulnerability.
1) Use-after-free (CVE-ID: CVE-2026-63802)
CWE-ID: CWE-416 - Use After Free
CVSSv4: 5.7 [CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]
The vulnerability allows a local user to cause a denial of service.
The vulnerability exists due to use-after-free in __blkcg_rstat_flush() when releasing multiple blkgs in the same blkcg concurrently. A local user can trigger concurrent blkg release operations to cause a denial of service.
The race occurs when one blkg removes another blkg's iostat entries via llist_del_all() while the other blkg is still being processed.
Remediation
Install update from vendor's website.
References
- https://git.kernel.org/stable/c/0ab5ee5a1badb58cbb2242617cb01a4972b1f2a2
- https://git.kernel.org/stable/c/5e5b7f2ef854936e95dceb6a2fdfefcb7152d2c6
- https://git.kernel.org/stable/c/96e545410c4f74c89d496c1d5d9ef8d08f14368b
- https://git.kernel.org/stable/c/afebe44facc48a61761e885bbb7f0380d4a603ec
- https://git.kernel.org/stable/c/bbebd9425cad3573d1527441753899b926525a0f