CVE-2025-46803

A flaw was found in Screen. The default mode for pseudo-terminals (PTYs) allocated by Screen was changed from 0620 to 0622. This vulnerability allows public writes to any PTYs in the system.

The change in the default PTY mode from 0620 to 0622 in Screen represents a significant security vulnerability because it directly exposes privileged terminal sessions to unauthorized local modification. In multi-user environments, PTYs act as communication endpoints between user shells and the system, and world-writable PTYs (0622) allow any user on the system to inject arbitrary input into another user’s terminal. Unlike a typical permission misconfiguration that may be considered a moderate flaw, this vulnerability can lead to active session hijacking, command injection, or data corruption in interactive processes like shells, editors, and administrative sessions. As PTYs are foundational to the UNIX security model for user isolation, this vulnerability undermines the integrity of user sessions and can result in privilege escalation when combined with poorly secured scripts or session contexts.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

No mitigation is currently available that meets Red Hat Product Security’s standards for usability, deployment, applicability, or stability.