CVE-2026-55467
Received Received - Intake

Heap-based Buffer Overflow in OpenPrinting CUPS

Publication date: 2026-10-15

Last updated on: 2026-10-15

Assigner: GitHub, Inc.

Description
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.

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Meta Information

Published
2026-10-15
Last Modified
2026-10-15
Generated
2026-10-16
AI Q&A
2026-10-15
EPSS Evaluated
N/A
NVD
CVE-2026-55467
EUVD
EUVD-2026-102204

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
OpenPrinting cups < 2.4.20

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-93 The product uses CRLF (carriage return line feeds) as a special element, e.g. to separate lines or records, but it does not neutralize or incorrectly neutralizes CRLF sequences from inputs.
CWE-94 The product constructs all or part of a code segment using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the syntax or behavior of the intended code segment.
CWE-150 The product receives input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could be interpreted as escape, meta, or control character sequences when they are sent to a downstream component.

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Executive Summary

CVE-2026-55467 is a vulnerability in OpenPrinting CUPS versions prior to 2.4.20. It involves insufficient sanitization of fax-related input values like destination-uri and pre-dial-string. These values bypass the control-character sanitizer and are passed directly to downstream filters. Attackers with job submission permissions can inject control characters into the filter options, potentially leading to code execution as the lp user if exploitable filters are used.

Detection Guidance

Check CUPS version with 'lpstat -v' or 'cups-config --version'. If version is below 2.4.20, the system is vulnerable. Inspect fax queue configurations for untrusted input handling. Monitor logs for unusual job submissions or filter errors.

Impact Analysis

If you use CUPS with a configured fax queue and an exploitable fax filter (like optional Foomatic), an attacker with job submission rights could inject control characters. This may lead to code execution as the lp user, allowing unauthorized actions on the system. The impact depends on the specific fax filter and system configuration.

Mitigation Strategies

Upgrade CUPS to version 2.4.20 or later. Disable fax queue functionality if not needed. Review and restrict user permissions for job submissions. Apply input validation for fax-related attributes in scheduler configurations.

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