Auth bypass in Openprinting Cups
CVE-2026-34990
OpenPrinting CUPS is an open source printing system for Linux and other Unix-like operating systems. In versions 2.4.16 and prior, a local unprivileged user can coerce cupsd into authenticating to an attacker-controlled localhost IPP service with a reusable Authorization: Local ... token. That token is enough to drive /admin/ requests on localhost, and the attacker can combine CUPS-Create-Local-Printer with printer-is-shared=true to persist a file:///... queue even though the normal FileDevice policy rejects such URIs. Printing to that queue gives an arbitrary root file overwrite; the PoC below uses that primitive to drop a sudoers fragment and demonstrate root command execution. At time of publication, there are no publicly available patches.
Vulnerability class: Broken Authentication
Published · last modified .
CVSS v3 metric
CVSS v3 base score 7.8 (High). Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H.
EPSS exploit prediction
EPSS: 0.002 (7.3th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 7th percentile — 7.3% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.003 · newest: 0.002 · change: -0.001
Affected products
- Openprinting Cups — versions <= 2.4.16
Weakness classification (CWE)
Public proof-of-concept exploits
References
- github.com/OpenPrinting/cups/security/advisories/GHSA-c54j-2vqw-wpwp (Exploit, Vendor Advisory)
Frequently asked questions
- What is CVE-2026-34990?
- CVE-2026-34990 is a high-severity vulnerability in Openprinting Cups, classified under Improper Authentication. CVSS score: 7.8/10. Published 2026-04-03.
- How severe is CVE-2026-34990?
- High severity. CVSS v3 base score is 7.8 out of 10.
- Is CVE-2026-34990 known to be exploited?
- 13 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.