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.

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: 2026-04-03
Last modified: 2026-07-20

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

https://github.com/OpenPrinting/cups/security/advisories/GHSA-f53q-7mxp-9gcr

Affected products (1)

cpe:2.3:a:openprinting:cups:*:*:*:*:*:*:*:*

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