CVE-2023-3961: Samba: smbd allows client access to unix domain sockets on the file system as root

Vulnerability summary

CVE-2023-3961 is a critical (CVSS 9.8) vulnerability in fedoraproject fedora. EPSS estimates a 2.69% chance of exploitation in the next 30 days, higher than 85.8% of scored vulnerabilities. 1 public exploit is recorded.

Timeline

1. 03-11-2023
   PublishedVulnerability first disclosed.
2. 20-11-2025
   Last modifiedVulnerability information updated.

Description

A path traversal vulnerability was identified in Samba when processing client pipe names connecting to Unix domain sockets within a private directory. Samba typically uses this mechanism to connect SMB clients to remote procedure call (RPC) services like SAMR LSA or SPOOLSS, which Samba initiates on demand. However, due to inadequate sanitization of incoming client pipe names, allowing a client to send a pipe name containing Unix directory traversal characters (../). This could result in SMB clients connecting as root to Unix domain sockets outside the private directory. If an attacker or client managed to send a pipe name resolving to an external service using an existing Unix domain socket, it could potentially lead to unauthorized access to the service and consequential adverse events, including compromise or service crashes.

• CWE-22Improper Limitation of a Pathname to a Restricted DirectoryThe product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory.