# CVE-2026-34978: OpenPrinting CUPS path traversal in RSS notifier

Source: https://junglewise.ai/threats/cve-2026-34978-openprinting-cups-path-traversal-in-rss-notifier  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-04-03. Updated: 2026-07-20  
License: CC BY 4.0 with a link back

CVE-2026-34978 · Severity: medium · CVSS 6.5 · Published 2026-04-03

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.

Technologies: [OpenPrinting Cups](https://junglewise.ai/threats/technologies/cups). Vendors: [OpenPrinting](https://junglewise.ai/threats/vendors/openprinting).

## Quick answers

**Is CVE-2026-34978 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-34978 being exploited in the wild.

**How severe is CVE-2026-34978?** Medium severity, with a CVSS score of 6.5, published 3 April 2026.

**Which products and versions are affected?** OpenPrinting Cups <= 2.4.16.

**Is there a fix for CVE-2026-34978?** A patch was published on 2026-04-03: Version 2.4.17 released to address the issue Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-34978 attacked?** It is attacked over the network, in an operating system.

**Am I affected by CVE-2026-34978?** Check whether you run OpenPrinting Cups at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## 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

## References

- [https://github.com/OpenPrinting/cups/security/advisories/GHSA-f53q-7mxp-9gcr](https://github.com/OpenPrinting/cups/security/advisories/GHSA-f53q-7mxp-9gcr)

## Related threats

- [OpenPrinting CUPS path traversal in banner processing](https://junglewise.ai/threats/cve-2026-61702-openprinting-cups-is-an-open-source-printing-system-for-linux-and)
- [OpenPrinting CUPS symlink-based file truncation in scheduler](https://junglewise.ai/threats/cve-2026-55480-openprinting-cups-is-an-open-source-printing-system-for-linux-and)
- [CUPS null pointer dereference in IPP job ticket handling](https://junglewise.ai/threats/cve-2026-107655-a-flaw-was-found-in-cups-when-processing-embedded-job-ticket)
- [OpenPrinting CUPS NULL pointer dereference in cupsdCheckJobs](https://junglewise.ai/threats/cve-2026-107888-openprinting-cups-before-2-4-20-contains-a-null-pointer)
- [CUPS scheduler case-insensitive username comparison in ACL validation](https://junglewise.ai/threats/cve-2026-87876-cups-scheduler-case-insensitive-username-comparison-in-acl)