Executive brief
OpenPrinting CUPS is a widely used printing system for Linux and Unix-like operating systems. A vulnerability in its RSS notification component allows a remote attacker to overwrite critical system files, such as the job cache. This can lead to the loss of print job history, service instability, and the corruption of system state files, potentially disrupting printing operations across an organization.
Technical details
A path traversal vulnerability exists in the RSS notifier of OpenPrinting CUPS (versions <= 2.4.16) due to insufficient normalization of the 'notify-recipient-uri' attribute. An attacker can provide a URI such as 'rss:///../job.cache', which the 'httpSeparateURI()' function fails to sanitize. Because the CUPS 'CacheDir' is typically group-writable by the 'lp' group (0770), the notifier—running as the 'lp' user—can use a temporary file and the 'rename()' system call to replace root-owned state files. This allows an unauthenticated remote IPP client to clobber 'job.cache' with RSS XML data. Upon a service restart, the 'cupsd' scheduler fails to parse the corrupted cache, causing all previously queued jobs to be lost. The issue is addressed in version 2.4.17.
Affected products
- OpenPrinting CUPS <= 2.4.16
Timeline
- 2026-03-31: advisory: Vendor advisory published on GitHub
- 2026-04-03: disclosed: NVD publication date
- 2026-04-03: patched: Version 2.4.17 released to address the issue