Bug 2454957 (CVE-2026-34978)

Summary: CVE-2026-34978 cups: OpenPrinting CUPS: Denial of Service via path traversal in RSS notifier
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: zdohnal
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: All   
OS: Linux   
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A flaw was found in OpenPrinting CUPS. A remote attacker can exploit a path traversal vulnerability in the RSS notifier by manipulating the `notify-recipient-uri`. This allows writing arbitrary RSS XML data to sensitive files outside the intended directory. This can lead to a denial of service (DoS) by corrupting critical system files, such as the job cache, causing the scheduler to fail and previously queued jobs to disappear.
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
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Bug Depends On: 2454990    
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Description OSIDB Bzimport 2026-04-03 22:01:51 UTC
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.