Bug 2530991 (CVE-2026-87876)

Summary: CVE-2026-87876 cups: OpenPrinting CUPS: Remaining case-insensitive username matching in scheduler side paths (CVE-2026-27447 follow-up)
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
Status: NEW --- QA Contact:
Severity: low Docs Contact:
Priority: low    
Version: unspecifiedCC: akhatavk, aos-team-art-private, asdas, dpaolell, jdelft, jupierce, lgarciaa, mbiarnes, ppalepu, ppostler, prdhamdh, rhel-process-autobot, sghai, sidsharm, suppawar, vlaad, watson-tool-maintainers, zdohnal
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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Two case-insensitive comparisons on request-derived usernames outside the main authorization path in CUPS's scheduler (printer ACL validation and private-attribute filtering) could allow bypass of username-based access controls in certain configurations.
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Description OSIDB Bzimport 2026-09-09 14:36:17 UTC 
The OpenPrinting CUPS project contains two instances of case-insensitive username comparisons in authorization-adjacent code paths that were not addressed by the original CVE-2026-27447 fix. These exist in the printer ACL validation logic and private-attribute filtering mechanisms:

1. scheduler/ipp.c:check_quotas() - uses _cups_strcasecmp() for printer ACL username matching
2. scheduler/policy.c:cupsdGetPrivateAttrs() - uses _cups_strcasecmp() for @OWNER and explicit username checks

These patterns were removed from the primary authorization path in the original CVE-2026-27447 fix but persist in these secondary paths.

Affected versions: < 2.4.20. No patched release listed at time of advisory (fixes committed but not yet released).

Reference: https://github.com/OpenPrinting/cups/security/advisories/GHSA-r8jp-q6fh-g5r2