Improper input validation in Linux kernel - CVE-2026-46243
Published: June 2, 2026
Vulnerability identifier: #VU133226
CSH Severity: Low
CVSS v4.0: CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:U/U:Clear
CVE-ID: CVE-2026-46243
CWE-ID: CWE-20
Exploitation vector: Local access
Exploit availability:
No public exploit available
Vendor: Linux Foundation
Affected software:
Linux kernel
Linux kernel
Detailed vulnerability description
The vulnerability allows a local user to disclose sensitive information, modify data, or cause a denial of service.
The vulnerability exists due to improper input validation in the cifs.spnego key description handling in fs/smb/client/cifs_spnego.c when processing userspace-created cifs.spnego keys through request_key(2) or add_key(2). A local user can supply a crafted cifs.spnego description to disclose sensitive information, modify data, or cause a denial of service.
The issue arises because authority-bearing fields such as pid, uid, creduid, and upcall_target may be treated by cifs.upcall as kernel-originating inputs.
How to mitigate CVE-2026-46243
Install security update from vendor's repository.
Sources
- https://git.kernel.org/stable/c/0aece6685fc80a8de492688ca2315fb86ec379c7
- https://git.kernel.org/stable/c/2035acfb17221729b1b8ac335e941868a04ca079
- https://git.kernel.org/stable/c/3da1fdf4efbc490041eb4f836bf596201203f8f2
- https://git.kernel.org/stable/c/7713bd320ed4fc3d08a227cd8e41242219a16981
- https://git.kernel.org/stable/c/91f89c1d83e80417629791fcef6af8140d7d01c8
- https://git.kernel.org/stable/c/9544559e59438a4b609b2fdfa0763d8360572824
- https://git.kernel.org/stable/c/a3bbda6502a9398b816fa2e71c9a3f955f58013d
- https://git.kernel.org/stable/c/cf20038657d6d4974349556a34e08fe0490bebbc
- http://www.openwall.com/lists/oss-security/2026/06/01/6
- https://github.com/manizada/CIFSwitch