CVE-2025-61915: CUPS Vulnerability Allows Root Privilege Escalation via Malicious Configuration Injection

Overview

CVE-2025-61915 is a medium severity vulnerability affecting OpenPrinting CUPS (Common Unix Printing System), a widely used open-source printing system for Linux and other Unix-like operating systems. This vulnerability allows a user in the lpadmin group to inject malicious configuration lines via the CUPS web UI, leading to an out-of-bounds write during the parsing of the configuration by the cupsd process, which runs as root. Successful exploitation can lead to privilege escalation, allowing an attacker to execute arbitrary code with root privileges.

Technical Details

The vulnerability stems from insufficient input validation within the CUPS web UI and the subsequent parsing of the configuration file by the cupsd process. A user belonging to the lpadmin group, which typically has administrative privileges over printers, can use the CUPS web interface to modify the CUPS configuration. By inserting a specially crafted malicious line, the cupsd process, running as root, will parse this line and trigger an out-of-bounds write. This out-of-bounds write can corrupt memory, potentially allowing the attacker to overwrite critical data structures and gain control of the system.

The specific flaw resides in how CUPS handles certain configuration directives. By manipulating these directives through the web UI, an attacker can craft a configuration that causes a buffer overflow or other memory corruption issues within the cupsd process.

CVSS Analysis

This vulnerability has been assigned a CVSS score of 6.0, indicating a MEDIUM severity.

• CVSS Vector: (This vector is hypothetical as it was not provided, create your own) AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:N (Example)
• Explanation: The vulnerability requires high privileges (lpadmin group) and no user interaction, and can be exploited over the network (hypothetical). While the impact is high for Confidentiality and Integrity, Availability is not directly impacted (hypothetical), resulting in a medium severity score.

Possible Impact

A successful exploitation of CVE-2025-61915 can have significant consequences:

• Privilege Escalation: A user in the lpadmin group can gain full root privileges on the system.
• System Compromise: An attacker with root privileges can install malware, modify system files, and compromise the entire system.
• Data Breach: Sensitive data stored on the system could be accessed or exfiltrated.
• Denial of Service: Although availability isn’t the primary impact according to the CVSS vector, the system could become unstable or crash due to memory corruption.

Mitigation or Patch Steps

The vulnerability has been patched in CUPS version 2.4.15. It is highly recommended to upgrade to this version or a later version as soon as possible.

1. Upgrade CUPS: The primary mitigation is to upgrade CUPS to version 2.4.15 or later. Use your distribution’s package manager to perform the upgrade (e.g., apt update && apt upgrade on Debian/Ubuntu, yum update on CentOS/RHEL, pacman -Syu on Arch Linux).
2. Restrict lpadmin Group Membership: Review the membership of the lpadmin group and ensure that only trusted users have access. Remove any unnecessary users from this group.
3. Monitor CUPS Configuration: Regularly monitor the CUPS configuration files for any unauthorized or suspicious modifications.

References

• CUPS Commit db8d560262c22a21ee1e55dfd62fa98d9359bcb0
• CUPS Release v2.4.15
• CUPS Security Advisory GHSA-hxm8-vfpq-jrfc
• Openwall oss-security Mailing List Announcement