A critical security flaw in the CUPS printing system has been discovered, allowing attackers to crash Linux systems and potentially bypass authentication mechanisms remotely.

The vulnerability, tracked as CVE-2025-58364, affects CUPS versions before 2.4.12 and poses significant risks to Linux environments across corporate and personal networks.

Vulnerability Details and Technical Impact

The vulnerability stems from unsafe deserialization and validation of printer attributes within the libcups library, specifically causing a null pointer dereference during IPP (Internet Printing Protocol) operations.

Security researcher zdohnal, who has extensive experience with CUPS development and maintains several printing-related repositories, disclosed the flaw through GitHub’s security advisory system.

The critical issue occurs when the system processes crafted printer attribute responses, particularly during the execution of ippValidateAttributes() function calls.

The vulnerability manifests in two key locations within the OpenPrinting codebase: cups/scheduler/ipp.c and libcupsfilters/cupsfilters/ipp.c.

The null dereference specifically happens during string validation loops where the system attempts to process malicious printer response data.

When exploited, the vulnerability triggers crashes in both the CUPS daemon and cups-browsed service, effectively disrupting printing capabilities across affected systems.

The attack vector requires network adjacency in default configurations, meaning attackers must be on the same local subnet as target machines.

However, systems with unpatched CVE-2024-47176 vulnerabilities and inadequate firewall configurations could face remote exploitation from public internet sources.

Exploitation Methods and Proof of Concept

The researcher provided detailed proof-of-concept demonstrations showing how attackers can exploit this vulnerability using relatively simple Python scripts.

The attack methodology involves setting up two machines on the same network – an attacker machine and a target machine – both running Ubuntu 24.04.2 LTS in the demonstrated scenarios.

The exploitation process requires the attacker to stop local CUPS services, install specific Python dependencies, and execute a malicious printer response script targeting the victim’s IP address.

The attack successfully crashes both CUPS version 2.4.7 and newer self-built instances, including CUPS 2.4.12, cups-browsed 2.1.1, libcupsfilters 2.1.1, and libppd 2.1.1.

For easier reproduction and debugging purposes, the researcher also provided local proof-of-concept code that developers can compile and execute to demonstrate the vulnerability’s behavior.

This approach allows security teams to understand the attack flow involving ipp_read_io() ippValidateAttributes() functions without requiring complex network setups.

This vulnerability presents significant risks to Linux infrastructure, as CUPS is installed by default on most Linux distributions and automatically listens for network printer announcements.

The remote denial-of-service capability means that a single attacker on a corporate network could potentially crash printing services across multiple workstations and servers simultaneously.

The attack’s effectiveness is particularly concerning because it targets fundamental printing infrastructure that many organizations rely upon for daily operations.

Since cups-browsed runs with elevated privileges and automatically discovers network printers, the vulnerability creates an attractive target for attackers seeking to disrupt business operations or gain initial access to network environments.

Organizations using older CUPS versions combined with unpatched cups-filters vulnerabilities face elevated risks, as the attack surface expands from local network threats to potential internet-based exploitation.

System administrators should immediately audit their CUPS installations and implement network-level protections while awaiting official patches from distribution maintainers.

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