Vulnerability · Published Apr 3, 2026 · Assigned by GitHub_M
CVE-2026-34978OpenPrinting CUPS: Path traversal in RSS notify-recipient-uri enables file write outside CacheDir/rss (and clobbering of job.cache)
Medium 6.5
In plain English
A medium-severity path traversal in cups from OpenPrinting. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 37% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine:v3.20 | cups | 2.4.18-r0 | ALPINE-CVE-2026-34978 |
| Alpine:v3.21 | cups | 2.4.18-r0 | ALPINE-CVE-2026-34978 |
| Alpine:v3.22 | cups | 2.4.18-r0 | ALPINE-CVE-2026-34978 |
| Alpine:v3.23 | cups | 2.4.18-r0 | ALPINE-CVE-2026-34978 |
| Alpine:v3.24 | cups | 2.4.18-r0 | ALPINE-CVE-2026-34978 |
| Debian:12 | cups | no fix listed | DEBIAN-CVE-2026-34978 |
| Debian:13 | cups | no fix listed | DEBIAN-CVE-2026-34978 |
| Debian:14 | cups | 2.4.17-1 | DEBIAN-CVE-2026-34978 |
| Ubuntu:22.04:LTS | cups | 2.4.1op1-1ubuntu4.20 | USN-8405-1 |
| Ubuntu:22.04:LTS | cups | 2.4.1op1-1ubuntu4.20 | UBUNTU-CVE-2026-34978 |
| Ubuntu:24.04:LTS | cups | 2.4.7-1.2ubuntu7.13 | USN-8405-1 |
| Ubuntu:24.04:LTS | cups | 2.4.7-1.2ubuntu7.13 | UBUNTU-CVE-2026-34978 |
| Ubuntu:25.10 | cups | 2.4.12-0ubuntu3.9 | USN-8405-1 |
| Ubuntu:25.10 | cups | 2.4.12-0ubuntu3.9 | UBUNTU-CVE-2026-34978 |
| Ubuntu:26.04:LTS | cups | 2.4.16-1ubuntu1.2 | UBUNTU-CVE-2026-34978 |
| Ubuntu:26.04:LTS | cups | 2.4.16-1ubuntu1.2 | USN-8405-1 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| OpenPrinting | cups | <= 2.4.16 |
Weakness: CWE-22 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L
References
- https://github.com/OpenPrinting/cups/security/advisories/GHSA-f53q-7mxp-9gcr x_refsource_CONFIRM