Improper input validation in cups - CVE-2026-34978

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Main Vulnerability Database Vulnerabilities #VU124815

Improper input validation in cups - CVE-2026-34978

Published: April 2, 2026


Vulnerability identifier: #VU124815
CSH Severity: Medium
CVSS v4: 6.9 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-34978
CWE-ID: CWE-20
Exploitation vector: Remote access
Exploit availability: No public exploit available

Vulnerability details

The vulnerability allows a remote attacker to overwrite arbitrary files within the CUPS CacheDir, including critical state files such as job.cache.

The vulnerability exists due to improper path validation in the RSS notifier component when processing attacker-controlled notify-recipient-uri values in IPP subscription requests. A remote attacker can send a specially crafted IPP request with a notify-recipient-uri containing directory traversal sequences (e.g., "rss:///../job.cache") to overwrite files outside the intended CacheDir/rss directory, leading to integrity and availability impacts.

The vulnerability specifically affects systems where the RSS notifier is enabled and untrusted clients can submit IPP Print-Job or Create-Printer-Subscription requests with subscription attributes. The default configuration with group-writable CacheDir (root:lp, 0770) enables overwriting of root-managed files via atomic rename operations performed by the lp-running notifier.


Affected software

cups
SUSE Linux Enterprise Server 12 SP5 LTSS Extended
SUSE Linux Enterprise Server for SAP Applications 12
SUSE Linux Enterprise Server 12
SUSE Linux Enterprise Server for SAP Applications 15
SUSE Linux Enterprise Server 15
SUSE Linux Enterprise Real Time 15
SUSE Linux Enterprise Desktop 15
SUSE Linux Enterprise Micro for Rancher
SUSE Linux Enterprise Micro
SUSE Linux Micro
Basesystem Module
Development Tools Module
Desktop Applications Module
openEuler
Ubuntu
Anolis OS
Fedora
cups-client-debuginfo
cups
cups-libs-debuginfo
cups-debuginfo
cups-devel
cups-libs
cups-libs-32bit
cups-client
cups-debugsource
cups-libs-debuginfo-32bit
libcupscgi1-debuginfo
libcupsppdc1
libcupsimage2
libcupscgi1
cups-config
libcups2-debuginfo
cups-ddk
libcupsmime1
libcups2
libcupsmime1-debuginfo
libcups2-32bit
libcupsppdc1-debuginfo
libcupsimage2-debuginfo
cups-ddk-debuginfo
libcups2-32bit-debuginfo
cups-help
cups-filesystem
cups-printerapp
cups-lpd
cups-ipptool
cups (Ubuntu package)
cups-doc

How to mitigate CVE-2026-34978

Install security update from vendor's website.

cups-client-debuginfo - addressed in versions 1.7.5-20.67.1, 2.2.7-150000.3.93.1
cups - addressed in versions 1.7.5-20.67.1, 2.2.7-150000.3.93.1
cups-libs-debuginfo - update to 1.7.5-20.67.1
cups-debuginfo - addressed in versions 1.7.5-20.67.1, 2.2.7-150000.3.93.1
cups-devel - addressed in versions 1.7.5-20.67.1, 2.2.7-150000.3.93.1
cups-libs - update to 1.7.5-20.67.1
cups-libs-32bit - update to 1.7.5-20.67.1
cups-client - addressed in versions 1.7.5-20.67.1, 2.2.7-150000.3.93.1
cups-debugsource - addressed in versions 1.7.5-20.67.1, 2.2.7-150000.3.93.1, 2.4.19-1.1
cups-libs-debuginfo-32bit - update to 1.7.5-20.67.1
libcupscgi1-debuginfo - update to 2.2.7-150000.3.93.1
libcupsppdc1 - update to 2.2.7-150000.3.93.1
libcupsimage2 - update to 2.2.7-150000.3.93.1
libcupscgi1 - update to 2.2.7-150000.3.93.1
cups-config - addressed in versions 2.2.7-150000.3.93.1, 2.4.19-1.1
libcups2-debuginfo - addressed in versions 2.2.7-150000.3.93.1, 2.4.19-1.1
cups-ddk - update to 2.2.7-150000.3.93.1
libcupsmime1 - update to 2.2.7-150000.3.93.1
libcups2 - addressed in versions 2.2.7-150000.3.93.1, 2.4.19-1.1
libcupsmime1-debuginfo - update to 2.2.7-150000.3.93.1
libcups2-32bit - update to 2.2.7-150000.3.93.1
libcupsppdc1-debuginfo - update to 2.2.7-150000.3.93.1
libcupsimage2-debuginfo - update to 2.2.7-150000.3.93.1
cups-ddk-debuginfo - update to 2.2.7-150000.3.93.1
libcups2-32bit-debuginfo - update to 2.2.7-150000.3.93.1
cups-client - addressed in versions 2.4.0-19, 2.4.7-13, 2.4.7-14
cups-debugsource - addressed in versions 2.4.0-19, 2.4.7-13, 2.4.7-14
cups - addressed in versions 2.4.0-19, 2.4.7-13, 2.4.7-14
cups-debuginfo - addressed in versions 2.4.0-19, 2.4.7-13, 2.4.7-14
cups-help - addressed in versions 2.4.0-19, 2.4.7-13, 2.4.7-14
cups-filesystem - addressed in versions 2.4.0-19, 2.4.7-13, 2.4.7-14
cups-printerapp - addressed in versions 2.4.0-19, 2.4.7-13, 2.4.7-14
cups-lpd - addressed in versions 2.4.0-19, 2.4.7-13, 2.4.7-14
cups-libs - addressed in versions 2.4.0-19, 2.4.7-13, 2.4.7-14
cups-ipptool - addressed in versions 2.4.0-19, 2.4.7-13, 2.4.7-14
cups-devel - addressed in versions 2.4.0-19, 2.4.7-13, 2.4.7-14
cups (Ubuntu package) - addressed in versions 2.4.1op1-1ubuntu4.20, 2.4.1op1-1ubuntu4.21, 2.4.7-1.2ubuntu7.13, 2.4.7-1.2ubuntu7.14, 2.4.12-0ubuntu3.9, 2.4.12-0ubuntu3.10, 2.4.16-1ubuntu1.2, 2.4.16-1ubuntu1.3
cups-doc - update to 2.4.10-8
cups - update to 2.4.10-8
cups-client - update to 2.4.10-8
cups-devel - update to 2.4.10-8
cups-ipptool - update to 2.4.10-8
cups-filesystem - update to 2.4.10-8
cups-libs - update to 2.4.10-8
cups-printerapp - update to 2.4.10-8
cups-lpd - update to 2.4.10-8
cups - addressed in versions 2.4.17-1.fc42, 2.4.17-1.fc43, 2.4.17-1.fc44, 2.4.17-1.fc45

External References

Related Security Bulletins