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Fencer Intel
low 3.0

CVE-2026-87876 json

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

published 2mo ago modified 4d ago also EUVD-2026-75089 , GHSA-r8jp-q6fh-g5r2

Unreviewed: the maintainers' own advisory

Published by the maintainers on their GitHub repository OpenPrinting/cups. GitHub has not reviewed it into the GitHub Advisory Database, so the affected packages and versions are the maintainers' word. Read the full advisory on GitHub.

cvss
3.0
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.3%
EPSS 0.3% chance of exploitation in 30 days, percentile 26%
public exploits
0
none known

Summary

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.

Patch / fix

  • Red Hat Red Hat Hardened Images 2.4.19-4.2.hum1
  • cups Debian 14 2.4.20-1

debian advisories DEBIAN-CVE-2026-87876

  • cups hummingbird 1 2.4.19-4.2.hum1
  • cups-lpd hummingbird 1 2.4.19-4.2.hum1
  • cups-libs hummingbird 1 2.4.19-4.2.hum1
  • cups-client hummingbird 1 2.4.19-4.2.hum1
  • cups-ipptool hummingbird 1 2.4.19-4.2.hum1
  • cups-filesystem hummingbird 1 2.4.19-4.2.hum1
  • cups-printerapp hummingbird 1 2.4.19-4.2.hum1

red hat advisories RHSA-2026:67568

  • cups openSUSE Tumbleweed 2.4.20-1.1

opensuse advisories openSUSE-SU-2026:12192-1

Is CVE-2026-87876 in your stack? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

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Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-87876 updated cvss 3.0

cups: OpenPrinting CUPS: Remaining case-insensitive username matching in scheduler side paths (CVE-2026-27447 follow-up)

  • Red Hat Enterprise Linux 6 cups, cups-lpd, cups-php, cups-libs, cups 2.4.10-18.el10_2 Red Hat Enterprise Linux 7 cups, cups-lpd, cups-libs, cups-client, cups-ipptool, cups-filesystem, +1 more Red Hat Enterprise Linux 8 cups, cups-lpd, cups-libs, cups-client, cups-ipptool, cups-filesystem, +1 more Red Hat Enterprise Linux 9 cups, cups-lpd, cups-libs, rhel9/cups, cups-client, cups-ipptool, +3 more Red Hat Enterprise Linux 10 cups 2.4.10-18.el10_2 Red Hat OpenShift Container Platform 4 openshift/ose-rhel-coreos-8
    affected: workaround, no fix available “Fix deferred”
  • Red Hat Hardened Images cups 2.4.19-4.2.hum1, cups-lpd 2.4.19-4.2.hum1, cups-libs 2.4.19-4.2.hum1, cups-client 2.4.19-4.2.hum1, cups-ipptool 2.4.19-4.2.hum1, cups-filesystem 2.4.19-4.2.hum1, +1 more
    fixed: vendor fix RHSA-2026:67568

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
Proof of concept is public
Automatable
no
Technical impact
partial
Assessed
2mo ago

Exploit prediction

0.33% chance of exploitation in the next 30 days, higher than 26% of all scored CVEs (FIRST EPSS, 2026-11-11).

Exploits and checks

  • github.com https://github.com/OpenPrinting/cups/security/advisories/GHSA-r8jp-q6fh-g5r2 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 3.0 CVSS:3.1/AV:A/AC:L/PR:L/UI:R/S:U/C:L/I:N/A:N

Affected products

  • Red Hat Red Hat Hardened Images
  • Red Hat Red Hat Enterprise Linux 10
  • Red Hat Red Hat Enterprise Linux 6
  • Red Hat Red Hat Enterprise Linux 7
  • Red Hat Red Hat Enterprise Linux 8
  • Red Hat Red Hat Enterprise Linux 9
  • Red Hat Red Hat OpenShift Container Platform 4

Classification

Weakness
  • CWE-178 Improper Handling of Case Sensitivity

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

The maintainers of OpenPrinting/cups published their own advisory on GitHub. Reviewed sources take precedence over it.