What’s Vulnerable › Vulnerabilities

CVE-2026-55453: CUPS ipp backend status-line injection can update queue PPD and lead to conditional RCE as lp via foomatic-rip

• Severity: low (CVSS 3.3 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.2% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2026-10-15 · updated 2026-10-20
• Weakness: CWE-74

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.

Affected products

• OpenPrinting cups: before 2.4.20 — fixed in 2.4.20

How to fix

Upgrade to a fixed version: OpenPrinting cups 2.4.20. Check the vendor advisory for mitigations.

References

• https://github.com/OpenPrinting/cups/commit/806e1b483096c51d59432468f4afdd7387d81dd7
• https://github.com/OpenPrinting/cups/commit/d41cf0616688721e9d435d54118c4c8a36ed596a
• https://github.com/OpenPrinting/cups/releases/tag/v2.4.20
• https://github.com/OpenPrinting/cups/security/advisories/GHSA-7hqf-mfhx-7r3v

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