Bug 2454947 (CVE-2026-34990)

Summary: CVE-2026-34990 cups: OpenPrinting CUPS: Privilege escalation via arbitrary file overwrite due to coerced authentication
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
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Hardware: All   
OS: Linux   
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A flaw was found in OpenPrinting CUPS. A local unprivileged user can exploit this vulnerability by coercing the `cupsd` service to authenticate to an attacker-controlled Internet Printing Protocol (IPP) service. This allows the user to create a persistent printer queue that can overwrite arbitrary files with root privileges. Successful exploitation can lead to privilege escalation and arbitrary root command execution.
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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: 2454993    
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Description OSIDB Bzimport 2026-04-03 22:01:22 UTC 
OpenPrinting CUPS is an open source printing system for Linux and other Unix-like operating systems. In versions 2.4.16 and prior, a local unprivileged user can coerce cupsd into authenticating to an attacker-controlled localhost IPP service with a reusable Authorization: Local ... token. That token is enough to drive /admin/ requests on localhost, and the attacker can combine CUPS-Create-Local-Printer with printer-is-shared=true to persist a file:///... queue even though the normal FileDevice policy rejects such URIs. Printing to that queue gives an arbitrary root file overwrite; the PoC below uses that primitive to drop a sudoers fragment and demonstrate root command execution. At time of publication, there are no publicly available patches.