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Fencer Vulns
low 2.5

CVE-2026-55467 json

CUPS fax option values bypass the CVE-2026-34980 control-character sanitizer (incomplete fix)

published 2026-10-15 24 d ago modified 2026-10-20 19 d ago also EUVD-2026-102204

cvss
2.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 7%
public exploits
0
none known

Summary

OpenPrinting CUPS is an open source printing system for Linux and other Unix-like operating systems. Prior to 2.4.20, the cupsdCreateJob option-string builder in scheduler/job.c maps attacker-controlled destination-uri and pre-dial-string values from a configured fax queue to the phone and faxPrefix options. Unlike ordinary IPP job attributes, these mapped fax values bypass the control-character sanitizer and are copied directly into the filter options argument. A user permitted to submit a job can therefore inject control characters into the downstream option stream. The reporter states that a downstream fax filter passing these values to a shell or modem command could execute code as lp, while the maintainer states that CUPS has no confidentiality or integrity impact because the only known code-executing filter is optional Foomatic and addressed separately, leaving possible disruption of the affected queue. This issue is fixed in version 2.4.20.

Patch / fix

  • openprinting cups 2.4.20
  • cups hummingbird 1 2.4.19-4.6.hum1
  • cups-lpd hummingbird 1 2.4.19-4.6.hum1
  • cups-libs hummingbird 1 2.4.19-4.6.hum1
  • cups-client hummingbird 1 2.4.19-4.6.hum1
  • cups-ipptool hummingbird 1 2.4.19-4.6.hum1
  • cups-filesystem hummingbird 1 2.4.19-4.6.hum1
  • cups-printerapp hummingbird 1 2.4.19-4.6.hum1

red hat advisories RHSA-2026:84421

  • cups openSUSE Tumbleweed 2.4.20-1.1

opensuse advisories openSUSE-SU-2026:12192-1

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-2026-55467 updated cvss 2.5

cups: cups: Denial of Service via unsanitized fax job attributes

  • Red Hat Hardened Images cups 2.4.19-4.6.hum1, cups-lpd 2.4.19-4.6.hum1, cups-libs 2.4.19-4.6.hum1, cups-client 2.4.19-4.6.hum1, cups-ipptool 2.4.19-4.6.hum1, cups-filesystem 2.4.19-4.6.hum1, +1 more
    fixed: vendor fix RHSA-2026:84421

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
24 d ago

Exploit prediction

0.18% chance of exploitation in the next 30 days, higher than 7% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • github.com https://github.com/OpenPrinting/cups/security/advisories/GHSA-69qc-prxg-h2c7 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 2.5 CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:L

Affected products

  • OpenPrinting cups

Classification

Weakness
  • CWE-93 Improper Neutralization of CRLF Sequences
  • CWE-94 Improper Control of Generation of Code
  • CWE-150 Improper Neutralization of Escape, Meta, or Control Sequences

References

Sources

Fencer Vulns 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.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.