Overview
The Common Vulnerabilities and Exposures (CVE) system has recently identified a critical security vulnerability, CVE-2025-23395, affecting Screen 5.0.0. This software, when run with setuid-root privileges, fails to drop these elevated privileges while operating on a user-supplied path. This vulnerability holds grave implications for all systems running the affected version of Screen as it allows unprivileged users to exploit this flaw and potentially gain root access, thereby compromising the entire system. Given the widespread use of Screen, this vulnerability holds potential for extensive damage and is of significant concern to system administrators and cybersecurity professionals alike.
Vulnerability Summary
CVE ID: CVE-2025-23395
Severity: High (7.8)
Attack Vector: Local
Privileges Required: Low
User Interaction: Required
Impact: System compromise, data leakage
Affected Products
Share secrets securely
Ameeba is private infrastructure for communication and sensitive work built on encrypted identity instead of exposed corporate identity systems.
Passwords, credentials, confidential files, screenshots, internal discussions, sensitive AI context, and private coordination should not become exposed across ordinary communication platforms.
- • Encrypted identity
- • Private Spaces for organizations and teams
- • End-to-end encrypted chat, calls, files, and notes
- • Sensitive AI work and protected collaboration
- • Built for information that cannot leak
Our mission is to secure human work alongside AI.
Product | Affected Versions
Screen | 5.0.0
How the Exploit Works
This vulnerability arises from the program’s mishandling of user-supplied paths. When Screen 5.0.0 runs with setuid-root privileges, it does not correctly drop these privileges when operating on a user-supplied path. This loophole allows an unprivileged user to create files in arbitrary locations with root ownership. The files also retain the invoking user’s group ownership and file mode 0644. In essence, all data written to the Screen PTY will be logged into this file. This situation can be exploited to escalate to root privileges, granting the attacker complete control over the compromised system.
Conceptual Example Code
Here’s a
conceptual
example of how the vulnerability might be exploited using a shell command:
# command to start Screen with setuid-root privileges
/usr/bin/screen -D -m -L /root/privileged.file
# command to write data to the Screen PTY
echo "malicious_command" > /dev/pts/X # X corresponds to the screen session PTY
# The above command logs the data into /root/privileged.file with root ownership
# The attacker can thus manipulate this file to gain root accessThis example serves to illustrate the potential exploitation of the vulnerability. Actual exploitation may vary based on the system’s configuration and the attacker’s capabilities.