# CVE-2026-34979: OpenPrinting CUPS heap buffer overflow in CUPS scheduler

Source: https://junglewise.ai/threats/cve-2026-34979-openprinting-cups-heap-buffer-overflow-in-cups-scheduler  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-04-03. Updated: 2026-07-24  
License: CC BY 4.0 with a link back

CVE-2026-34979 · Severity: medium · CVSS 5.3 · Published 2026-04-03

OpenPrinting CUPS is a widely used open-source printing system for Linux and Unix-like operating systems. A vulnerability in the system's scheduler allows an attacker to send a specially crafted print job that can crash the printing service. This could lead to a denial-of-service, preventing users from printing documents across the network.

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

## Quick answers

**Is CVE-2026-34979 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-34979 being exploited in the wild.

**How severe is CVE-2026-34979?** Medium severity, with a CVSS score of 5.3, published 3 April 2026.

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

**Is there a fix for CVE-2026-34979?** A patch was published on 2026-04-03: Version 2.4.17 released to address the overflow Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-34979 attacked?** It is attacked over the network, in an operating system.

**Am I affected by CVE-2026-34979?** 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 heap-based buffer overflow exists in the CUPS scheduler (cupsd) within the `get_options()` function in `scheduler/job.c`. The vulnerability is caused by a discrepancy between how `ipp_length()` calculates the required buffer size for job attributes and how the attributes are actually serialized. Specifically, `ipp_length()` skips URI attributes, but `get_options()` still writes certain URI attributes (such as `job-uuid` and `job-authorization-uri`) to the buffer without performing bounds checks. A remote, unauthenticated attacker can exploit this by submitting a print job with maliciously large URI attributes, leading to memory corruption, a service crash (DoS), or potentially arbitrary code execution. The issue is addressed in version 2.4.17.

## Affected products

- OpenPrinting CUPS <= 2.4.16

## Timeline

- 2026-03-31: advisory: GitHub Security Advisory published by OpenPrinting
- 2026-04-03: disclosed: CVE-2026-34979 published
- 2026-04-03: patched: Version 2.4.17 released to address the overflow

## References

- [https://github.com/OpenPrinting/cups/security/advisories/GHSA-6qxf-7jx6-86fh](https://github.com/OpenPrinting/cups/security/advisories/GHSA-6qxf-7jx6-86fh)

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