Double free in Linux kernel - CVE-2026-89767
Published: September 12, 2026
Vulnerability identifier: #VU149041
CSH Severity: Low
CVSS v4: 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]
CVE-ID: CVE-2026-89767
CWE-ID: CWE-415
Exploitation vector: Local access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a local user to cause a denial of service.
The vulnerability exists due to a double release in ovl_create_real() in OverlayFS when handling a casefold mismatch during directory creation. A local user can mark the internal work subdirectory as casefolded after mounting an overlay filesystem and trigger a directory copy-up to cause a denial of service.
Subsequent creation operations under the affected parent directory can block indefinitely on its i_rwsem.
Affected software
Linux kernel
How to mitigate CVE-2026-89767
Install security update from vendor's repository.