Is CVE-2026-34978 in the CISA KEV catalog?

No. CVE-2026-34978 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2026-34978?

CVE-2026-34978 has a CVSS v3 base score of 6.5 (Moderate).

What is the EPSS score for CVE-2026-34978?

CVE-2026-34978 has an EPSS score of 0.41% (33th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2026-34978?

Upgrade cups on debian unstable to 2.4.17-1 or later. Fixes are available for 5 affected products.

CVE & CISA-KEV Catalog

CVE-2026-34978

MEDIUM

6.5

CVSS v3

NVD

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.

CWE-22Path Traversal

How to fix

Remediation Available

cupsDebian

Fixed in:2.4.17-1CVE-2026-34978

cupsRed Hat / RHEL

Fixed in:main@srcRHSA-2026:8814

Fixed in:main@x86_64RHSA-2026:8814

Fixed in:main@noarchRHSA-2026:8814

Fixed in:main@aarch64RHSA-2026:8814

cupsRocky

Fixed in:main@aarch64RHSA-2026:8814

Fixed in:main@srcRHSA-2026:8814

Fixed in:main@x86_64RHSA-2026:8814

Fixed in:main@noarchRHSA-2026:8814

cupsUbuntu

Fixed in:2.4.1op1-1ubuntu4.20USN-8405-1

Fixed in:2.4.7-1.2ubuntu7.13USN-8405-1

Fixed in:2.4.12-0ubuntu3.9USN-8405-1

cups-daemonUbuntu

Fixed in:2.4.1op1-1ubuntu4.20USN-8405-1

Fixed in:2.4.7-1.2ubuntu7.13USN-8405-1

Fixed in:2.4.12-0ubuntu3.9USN-8405-1

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityLow

Privileges RequiredNone

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityNone

IntegrityLow

AvailabilityLow

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

Exploit Intelligence

0.41%probability of exploitation in 30 days

33rdpercentile

Low risk: more likely to be exploited than 33% of all known CVEs.

References

Exploit1

github.com

Related Vulnerabilities

Other CWE-22 (Path Traversal) vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2024-23897	Critical	9.8	100%	KEV + Ransom	Fix
CVE-2023-32315	High	8.6	100%	KEV	Fix
CVE-2022-29464	Critical	9.8	100%	KEV + Ransom	-
CVE-2021-26086	Medium	5.3	100%	KEV	Fix
CVE-2021-22005	Critical	9.8	100%	KEV + Ransom	Fix
CVE-2020-5902	Critical	9.8	100%	KEV + Ransom	Fix

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-04-16.