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CVE-2026-34978

MEDIUMCVSS 6.5/10EPSS 0.41%

Last modified

CVE-2026-34978 is a medium-severity vulnerability rated 6.5/10 on the CVSS scale. 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 .. EPSS estimates a 0.41% chance of exploitation in the next 30 days.

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.

Metrics

CVSS 3.1
6.5/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L

EPSS Probability
0.41%

32.4th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

VendorProductVersions
OpenprintingCups<= 2.4.16

References

Timeline

Published
Last Modified
Status
Analyzed

Frequently Asked Questions

What is 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.
How severe is CVE-2026-34978?
CVE-2026-34978 has a CVSS score of 6.5/10 (MEDIUM severity). The EPSS model estimates a 0.41% probability of exploitation in the next 30 days.
How do I fix CVE-2026-34978?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2026-34978?

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Source: NVD / NIST