CVE-2026-55467 OpenPrinting CVE debrief

Who should care

Defenders responsible for Linux and Unix-like systems with CUPS fax queues should assess exposure and apply the patch to prevent potential code injection and disruption. This includes operators, platform administrators, vulnerability management teams, and security teams who need to review and mitigate this vulnerability.

Why it matters

Defenders should prioritize verifying exposure of CUPS fax queues and applying the patch to prevent potential code injection and disruption.

• Potential code execution as lp via crafted fax queue configurations
• Disruption of affected CUPS fax queues

Technical summary

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, bypassing the control-character sanitizer. This allows a user permitted to submit a job to inject control characters into the downstream option stream, potentially leading to code execution as lp. The issue is fixed in version 2.4.20 of OpenPrinting CUPS, addressing the code injection vulnerability in fax queue configurations.

Defensive priority

Defenders should prioritize verifying exposure of CUPS fax queues and applying the patch.

Recommended defensive actions

• Verify CUPS fax queue configurations for potential exposure
• Apply the patch to update to version 2.4.20
• Monitor CUPS job submissions for suspicious activity
• Review compensating controls for exposed systems while remediation is scheduled and verified
• Check relevant monitoring, detection, and logs for exposed assets that need extra review
• Track exceptions, retest remediated assets, and close the item only after evidence is documented
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up

Evidence notes

The CVE record and NVD entry provide details on the vulnerability and its fix. The reporter and maintainer provide insights into the potential impact and mitigations. The vulnerability has a CVSS score of 2.5 and is considered low severity. The issue was reported and fixed in version 2.4.20 of OpenPrinting CUPS. There are no known exploits in the wild, but defenders should verify exposure and apply the patch.

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.