# CVE-2026-87876: Cups: openprinting cups: remaining case-insensitive username matching in scheduler side paths (cve-2026-27447 follow-up)

Status: published. Published: 2026-09-09. Updated: 2026-11-06.

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.

## Remediation

- workaround: Fixed on upstream master branch with commit f56844d and for versions 2.4.x with commit 88e67c0. (source: CNA: redhat)

## Affected products and versions

- Red Hat / Red Hat Hardened Images (cups-main): ≥ 2.4.19-4.2.hum1; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 10 (cups): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 6 (cups): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 7 (cups): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 8 (cups): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 9 (cups): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 9 (rhel9/cups): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat OpenShift Container Platform 4 (openshift/ose-rhel-coreos-8): Version range not reported. Source: CNA: redhat

## Severity and prioritization

- CVSS 3.1: 3 (low); CVSS:3.1/AV:A/AC:L/PR:L/UI:R/S:U/C:L/I:N/A:N; source: CNA: redhat

- CISA KEV: No listing in collected sources

- EPSS: 0.33% as of 2026-11-06; percentile 26.00%

- SSVC: exploitation poc; automatable no; technical impact partial; source ADP: CISA-ADP

- Weaknesses: CWE-178

## Exploit evidence

- exploit: https://github.com/OpenPrinting/cups/security/advisories/GHSA-r8jp-q6fh-g5r2 (ADP: CISA-ADP)

## References

- https://access.redhat.com/errata/RHSA-2026:67568 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/security/cve/CVE-2026-87876 (CNA: redhat; vdb-entry, x_refsource_REDHAT)

- https://bugzilla.redhat.com/show_bug.cgi?id=2530991 (CNA: redhat; issue-tracking, x_refsource_REDHAT)

- https://github.com/OpenPrinting/cups/commit/88e67c00c130a45f3a1edf36686f7a0b2982fef8 (CNA: redhat)

- https://github.com/OpenPrinting/cups/commit/f56844dbe4a54a9f8e1aeb3b913fbee614156bdb (CNA: redhat)

- https://github.com/OpenPrinting/cups/security/advisories/GHSA-r8jp-q6fh-g5r2 (CNA: redhat)

- https://github.com/OpenPrinting/cups/security/advisories/GHSA-r8jp-q6fh-g5r2 (ADP: CISA-ADP; exploit)

## Provenance

- CNA: redhat: https://www.cve.org/CVERecord?id=CVE-2026-87876; retrieved 2026-11-06; source updated 2026-11-06

- FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2026-87876; retrieved 2026-11-06; source updated Not reported

Revision: 25e911c7a2c1a43eb2acc4a66693b30aa5790e591de81cab60c534491c430077

Canonical: https://y2.dev/cve/CVE-2026-87876

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