Linux · Linux Kernel · CVE-2026-46243
**Name of the Vulnerable Software and Affected Versions**
Linux kernel versions prior to 7.0.11
Linux kernel versions prior to 6.18.34
Linux kernel versions prior to 6.12.92
Linux kernel versions prior to 6.6.142
Linux kernel versions prior to 6.1.175
Linux kernel versions prior to 5.15.209
Linux kernel versions prior to 5.10.258
**Description**
A privilege escalation issue exists in the Linux kernel's CIFS client implementation. The `cifs get spnego key()` function within the `cifs.upcall` tool of the `cifs-utils` package lacks proper authentication for a critical function. Specifically, `cifs.spnego` key descriptions contain authority-bearing fields—including `pid`, `uid`, `creduid`, and `upcall target`—which `cifs.upcall` incorrectly treats as inputs originating from the kernel. A local attacker can use `request key(2)` or `add key(2)` to create keys of this type in userspace, allowing these fields to be supplied without a legitimate CIFS origin. This can enable an attacker to impersonate other users, bypass authentication in SMB mount operations, execute arbitrary code, and escalate privileges to root level. This issue has been demonstrated to facilitate container escapes from Docker environments to the host system.
**Recommendations**
Update to Linux kernel version 7.0.11 or newer.
Update to Linux kernel version 6.18.34 or newer.
Update to Linux kernel version 6.12.92 or newer.
Update to Linux kernel version 6.6.142 or newer.
Update to Linux kernel version 6.1.175 or newer.
Update to Linux kernel version 5.15.209 or newer.
Update to Linux kernel version 5.10.258 or newer.