Incorrect Implementation of Authentication Algorithm in Linux kernel - CVE-2026-64389

CSH
CYBERSECURITY HELP
Sign In REGISTER
 
Main Vulnerability Database Vulnerabilities #VU139576

Incorrect Implementation of Authentication Algorithm in Linux kernel - CVE-2026-64389

Published: July 27, 2026


Vulnerability identifier: #VU139576
CSH Severity: Low
CVSS v4: 5.3 [CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-64389
CWE-ID: CWE-303
Exploitation vector: Remote access
Exploit availability: No public exploit available

Vulnerability details

The vulnerability allows a remote user to modify session key material.

The vulnerability exists due to improper authentication logic in ksmbd NTLMv2 authentication handling when processing SMB3 multichannel binding session setup requests with KEY_XCH. A remote user can send a binding session setup with a bad NT proof and KEY_XCH to modify session key material.

The issue occurs on an existing session because the failed authentication path does not expire binding sessions.


Affected software

Linux kernel
Debian Linux
Ubuntu
linux-nvidia-tegra (Ubuntu package)
linux (Ubuntu package)
linux-realtime (Ubuntu package)
linux-gcp (Ubuntu package)
linux-oracle (Ubuntu package)
linux-aws (Ubuntu package)
linux-raspi (Ubuntu package)
linux-azure (Ubuntu package)
linux-nvidia (Ubuntu package)
linux-ibm (Ubuntu package)
linux-nvidia-bos (Ubuntu package)
linux-hwe-7.0 (Ubuntu package)
linux-gcp-7.0 (Ubuntu package)
linux-azure-7.0 (Ubuntu package)
linux-oracle-7.0 (Ubuntu package)
linux-oem-7.0 (Ubuntu package)
linux-gke (Ubuntu package)
linux-aws-7.0 (Ubuntu package)
linux-nvidia-7.0 (Ubuntu package)
linux (Debian package)

How to mitigate CVE-2026-64389

Install security update from vendor's repository.

Linux kernel - update to 7.0 rc3
linux-nvidia-tegra (Ubuntu package) - update to 6.8.0-1036.39
linux (Ubuntu package) - update to 7.0.0-31.31
linux-realtime (Ubuntu package) - update to 7.0.0-31.31.1
linux-gcp (Ubuntu package) - update to 7.0.0-1011.11
linux-oracle (Ubuntu package) - update to 7.0.0-1011.11
linux-aws (Ubuntu package) - update to 7.0.0-1012.12
linux-raspi (Ubuntu package) - update to 7.0.0-1019.19
linux-azure (Ubuntu package) - update to 7.0.0-1014.14
linux-nvidia (Ubuntu package) - update to 7.0.0-1018.18
linux-ibm (Ubuntu package) - update to 7.0.0-1013.13
linux-nvidia-bos (Ubuntu package) - update to 7.0.0-2018.18
linux-hwe-7.0 (Ubuntu package) - update to 7.0.0-31.31~24.04.1
linux-gcp-7.0 (Ubuntu package) - update to 7.0.0-1011.11~24.04.1
linux-azure-7.0 (Ubuntu package) - update to 7.0.0-1014.14~24.04.1
linux-oracle-7.0 (Ubuntu package) - update to 7.0.0-1011.11~24.04.1
linux-oem-7.0 (Ubuntu package) - update to 7.0.0-1013.13
linux-gke (Ubuntu package) - update to 7.0.0-1006.7
linux-aws-7.0 (Ubuntu package) - update to 7.0.0-1012.12~24.04.1
linux-nvidia-7.0 (Ubuntu package) - update to 7.0.0-1018.18~24.04.1
linux (Debian package) - update to 6.12.115-2

External References

Related Security Bulletins