CVE-2026-55453
Received Received - Intake

Integer Overflow in OpenPrinting CUPS Prior to 2.4.20

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 backend/ipp.c quote_string() function preserves carriage-return and line-feed characters in a remote printer-controlled marker-message before report_attr() writes the value to the scheduler status stream. The scheduler can parse an injected newline as a separate PPD: control line and persist an attacker-selected PPD keyword. The reporter demonstrated that a later print job on a Foomatic-backed queue could consume an injected FoomaticRIPCommandLine value and execute in the filter context as lp. 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-2026-55453
EUVD
EUVD-2026-102207

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
KEV Icon
CWE ID Description
CWE-77 The product constructs all or part of a command using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended command when it is sent to a downstream component.
CWE-78 The product constructs all or part of an OS command using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended OS command when it is sent to a downstream component.
CWE-74 The product constructs all or part of a command, data structure, or record using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify how it is parsed or interpreted when it is sent to a downstream component.

Attack-Flow Graph

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Executive Summary

CVE-2026-55453 is a vulnerability in OpenPrinting CUPS versions prior to 2.4.20. It involves improper handling of carriage-return and line-feed characters in printer-controlled status messages. Attackers can inject newline characters into these messages, which the scheduler interprets as separate control lines. This allows writing attacker-selected PPD keywords into the queue configuration file. If the queue uses a Foomatic-backed filter, a later print job could execute the injected command as the lp user.

Detection Guidance

To detect CVE-2026-55453, check your CUPS version with 'cups-config --version' or 'dpkg -l cups'. If it is below 2.4.20, the system is vulnerable. Inspect PPD files in /etc/cups/ppd/ for unexpected 'FoomaticRIPCommandLine' entries. Monitor CUPS logs for malformed IPP status messages containing newlines or carriage returns.

Impact Analysis

This vulnerability allows conditional remote code execution as the lp user under specific conditions. An attacker would need control over a printer in your network, your system must use a Foomatic-backed print queue, and a print job must process the malicious status. The impact is limited to the lp user's privileges and requires multiple specific conditions to be met.

Compliance Impact

This vulnerability does not directly impact GDPR or HIPAA compliance as it does not involve unauthorized access to personal data or protected health information. The issue is limited to conditional remote code execution as user 'lp' under specific conditions, which does not inherently violate these standards.

Mitigation Strategies

Upgrade CUPS to version 2.4.20 or later immediately. If upgrading is not possible, restrict access to IPP printers and disable Foomatic-backed queues. Review and remove any suspicious PPD files in /etc/cups/ppd/. Monitor for unusual print job activity or unauthorized commands.

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