Path Traversal in Openprinting Cups
CVE-2026-34978
OpenPrinting CUPS is an open source printing system for Linux and other Unix-like operating systems. In versions 2.4.16 and prior, the RSS notifier allows .. path traversal in notify-recipient-uri (e.g., rss:///../job.cache), letting a remote IPP client write RSS XML bytes outside CacheDir/rss (anywhere that is lp-writable). In particular, because CacheDir is group-writable by default (typically root:lp and mode 0770), the notifier (running as lp) can replace root-managed state files via temp-file + rename(). This PoC clobbers CacheDir/job.cache with RSS XML, and after restarting cupsd the scheduler fails to parse the job cache and previously queued jobs disappear. At time of publication, there are no publicly available patches.
Vulnerability class: Path Traversal (Directory Traversal)
Published · last modified .
CVSS v3 metric
CVSS v3 base score 6.5 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L.
EPSS exploit prediction
EPSS: 0.004 (34.8th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 35th percentile — 34.8% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.004 · newest: 0.004 · change: +0.000
Affected products
- Openprinting Cups — versions <= 2.4.16
Weakness classification (CWE)
References
- github.com/OpenPrinting/cups/security/advisories/GHSA-f53q-7mxp-9gcr (Exploit, Vendor Advisory)
Frequently asked questions
- What is CVE-2026-34978?
- CVE-2026-34978 is a medium-severity vulnerability in Openprinting Cups, classified under Path Traversal. CVSS score: 6.5/10. Published 2026-04-03.
- How severe is CVE-2026-34978?
- Medium severity. CVSS v3 base score is 6.5 out of 10.