CVE-2024-26822
MEDIUMCVSS VectorNVD
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N
Lifecycle Timeline
3DescriptionNVD
In the Linux kernel, the following vulnerability has been resolved:
smb: client: set correct id, uid and cruid for multiuser automounts
When uid, gid and cruid are not specified, we need to dynamically set them into the filesystem context used for automounting otherwise they'll end up reusing the values from the parent mount.
AnalysisAI
This vulnerability in the Linux kernel's SMB client implementation fails to properly set user identity attributes (uid, gid, cruid) during multiuser automount operations, causing child mounts to inherit credentials from the parent mount instead of dynamically assigning correct values. A local attacker with unprivileged user access can exploit this to gain unauthorized access to files or perform operations with elevated privileges on SMB shares, potentially leading to privilege escalation. The vulnerability affects multiple kernel versions from 5.15.124 through 6.8-rc4, patches are available from the kernel maintainers, and the EPSS score of 0.03% indicates low real-world exploitation probability despite the moderate CVSS rating.
Technical ContextAI
The vulnerability resides in the Linux kernel's SMB (Server Message Block) client implementation, specifically in the automounting subsystem that handles multiuser SMB mount scenarios. When automounting child filesystems, the code fails to dynamically configure the filesystem context (fsctx) with correct uid, gid, and cruid values when these are not explicitly specified by the user. Instead, the child mount inherits these credential values from the parent mount context, violating the principle of least privilege in multiuser environments. This is a configuration/initialization issue rather than a memory corruption or authentication bypass; the root cause falls under improper input handling or missing validation (CWE category concerning default/inherited values). The affected products are identified via CPE as Linux kernel versions including 5.15.124, 6.1.54, and the 6.8 release candidate series (rc1 through rc4), as well as broader version ranges indicated by wildcard CPE entries.
RemediationAI
Apply the available kernel patches from the upstream Linux kernel project by upgrading to a kernel version that includes one of the referenced commits (2ceba8ae1bd1f5589548cb722a5c583ca3a2dede, 4508ec17357094e2075f334948393ddedbb75157, 4a6e4c56721a3e6e2550b72ec56aab306c4607a7, 7590ba9057c6d74c66f3b909a383ec47cd2f27fb, or c2aa2718cda2d56b4a551cb40043e9abc9684626). Most Linux distributions will address this through standard security updates; users should apply kernel updates from their distribution vendor (Red Hat, Ubuntu, Debian, etc.) as they become available. For systems using multiuser SMB mounts, explicitly specify uid, gid, and cruid mount options rather than relying on defaults, and verify that each user or mount point is configured with appropriate identity attributes. Restrict SMB mount permissions to trusted users and apply principle of least privilege to credential delegation. Monitor kernel.org (https://git.kernel.org/stable) for stable branch updates and follow your distribution's security advisory channels (e.g., Red Hat Security Advisories, Ubuntu Security Notices) for official patch availability.
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External POC / Exploit Code
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