CVE-2026-34978
CVE-2026-34978 is a medium-severity vulnerability in Openprinting Cups with a CVSS 3.x base score of 6.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-22.
Key facts
- Severity: Medium (CVSS 3.x base score 6.5)
- EPSS exploit prediction: 0% (34th percentile)
- Actively exploited: Not listed in CISA KEV
- EU (EUVD) id: EUVD-2026-18884
- Weakness: CWE-22
- Affected product: Openprinting Cups
- Published:
- Last modified:
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.
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 3.x base score of 6.5, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity low, and availability low.
- Is CVE-2026-34978 being actively exploited?
- It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (34th percentile), an estimate of the probability of exploitation in the next 30 days.
- What products are affected by CVE-2026-34978?
- CVE-2026-34978 affects Openprinting Cups. See the affected-products list for the exact vulnerable versions.
- How do I fix CVE-2026-34978?
- Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
- Does CVE-2026-34978 have an EU (EUVD) identifier?
- Yes. CVE-2026-34978 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-18884.
- When was CVE-2026-34978 published?
- CVE-2026-34978 was published on 2026-04-03 and last updated on 2026-07-20.
References
Affected products (1)
- cpe:2.3:a:openprinting:cups:*:*:*:*:*:*:*:*
More vulnerabilities in Openprinting Cups
- CVE-2025-58060 — High (CVSS 8.0): OpenPrinting CUPS is an open source printing system for Linux and other Unix-like operating systems. In versions 2.4.12…
- CVE-2026-34990 — High (CVSS 7.8): OpenPrinting CUPS is an open source printing system for Linux and other Unix-like operating systems. In versions 2.4.16…
- CVE-2026-34980 — High (CVSS 7.5): OpenPrinting CUPS is an open source printing system for Linux and other Unix-like operating systems. In versions 2.4.16…
- CVE-2023-32324 — High (CVSS 7.5): OpenPrinting CUPS is an open source printing system. In versions 2.4.2 and prior, a heap buffer overflow vulnerability…
- CVE-2023-4504 — High (CVSS 7.0): Due to failure in validating the length provided by an attacker-crafted PPD PostScript document, CUPS and libppd are…
- CVE-2022-26691 — Medium (CVSS 6.7): A logic issue was addressed with improved state management. This issue is fixed in Security Update 2022-003 Catalina,…
All CVEs affecting Openprinting Cups →
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