Memory leak in Linux kernel - CVE-2026-64139
Published: July 20, 2026
Vulnerability identifier: #VU138503
CSH Severity: Medium
CVSS v4.0: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Green
CVE-ID: CVE-2026-64139
CWE-ID: CWE-401
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vendor: Linux Foundation
Affected software:
Linux kernel
Linux kernel
Detailed vulnerability description
The vulnerability allows a remote attacker to cause a denial of service.
The vulnerability exists due to a memory leak in set_posix_acl_entries_dacl() in ksmbd when processing a malicious or malformed file with enough POSIX ACL entries to trigger the DACL size overflow check. A remote attacker can send or access a crafted file to cause a denial of service.
The issue occurs because cleanup is skipped when overflow handling breaks out of ACE-building loops.
How to mitigate CVE-2026-64139
Install security update from vendor's repository.
Sources
- https://git.kernel.org/stable/c/0e198f09cb2a554c04de0fea4e790f1250a943ca
- https://git.kernel.org/stable/c/519fb0a42ce5d7e46935577309fb282a5f2c6ea3
- https://git.kernel.org/stable/c/9d378e17c864da08c3a4df41dae92cfa6468b00a
- https://git.kernel.org/stable/c/af92ee994cc7f7e83a41c2025f32257a2f82a7ef
- https://git.kernel.org/stable/c/eced48cb08f07393a5ea770fdd1026452883c3ad