Memory leak in Linux kernel - CVE-2026-64139

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Main Vulnerability Database Vulnerabilities #VU138503

Memory leak in Linux kernel - CVE-2026-64139

Published: July 20, 2026


Vulnerability identifier: #VU138503
CSH Severity: Medium
CVSS v4: 8.7 [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]
CVE-ID: CVE-2026-64139
CWE-ID: CWE-401
Exploitation vector: Remote access
Exploit availability: No public exploit available

Vulnerability details

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.


Affected software

Linux kernel
Ubuntu
linux-ibm (Ubuntu package)
linux-aws (Ubuntu package)
linux-nvidia (Ubuntu package)
linux-nvidia-bos (Ubuntu package)

How to mitigate CVE-2026-64139

Install security update from vendor's repository.

Linux kernel - update to 7.0 rc3
linux-ibm (Ubuntu package) - addressed in versions 7.0.0-1008.8, 7.0.0-1010.10
linux-aws (Ubuntu package) - addressed in versions 7.0.0-1009.9, 7.0.0-1015.15
linux-nvidia (Ubuntu package) - addressed in versions 7.0.0-1016.16, 7.0.0-1016.16~24.04.1
linux-nvidia-bos (Ubuntu package) - update to 7.0.0-2016.16

External References

Related Security Bulletins