Description

A flaw was found in CUPS. When processing embedded job ticket comments within documents, the service improperly handles specific IPP attributes, causing an unhandled null pointer dereference. An unauthenticated attacker permitted to submit jobs to a shared printer queue can send a crafted Internet Printing Protocol (IPP) request to crash the print daemon, resulting in a temporary Denial of Service (DoS) for all printing services.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "4.0",
  "pubDate": "2026-10-09T09:17:08.120Z",
  "pubdate": "2026-10-09T09:17:08.120Z",
  "executiveSummary": "A critical vulnerability exists in the Common Unix Printing System (CUPS) print daemon resulting from the improper handling of embedded job ticket comments within Internet Printing Protocol (IPP) requests.\nThe flaw manifests as a null pointer dereference, which occurs when the service processes specifically crafted IPP attributes.\nAn unauthenticated attacker with network access to a shared printer queue can exploit this vulnerability by submitting a malicious print job containing the malformed IPP request.\nSuccessful exploitation triggers an unhandled exception, causing the CUPS print daemon to crash immediately.\nThe primary impact is a Denial of Service (DoS), rendering all printing services unavailable until the daemon is manually restarted.\nThis vulnerability poses a significant risk to shared printing environments, as it allows unauthorized remote actors to disrupt essential enterprise infrastructure without requiring prior authentication.",
  "technicalDetails": "The root cause of this vulnerability lies in the memory management logic within the CUPS IPP processing subsystem. When the daemon receives a request, it parses the Job Template attributes embedded within the document's job ticket.\nDuring the parsing process, specific malformed or unexpected IPP attributes fail to be validated correctly, leading the application logic to reference a null pointer during the attribute evaluation phase.\nThe exploitation flow begins when an attacker identifies an accessible IPP port (typically TCP 631) exposed by the target CUPS server. The attacker crafts a request payload that includes specific, non-compliant IPP attribute structures within the document comments field.\nWhen the CUPS daemon attempts to process these attributes, the lack of input validation for these fields causes the software to perform an operation on a memory address that has not been initialized or mapped, resulting in a segmentation fault or a null pointer dereference exception.\nBecause this error occurs within the core print daemon, it causes the process to terminate unexpectedly. The daemon is often unable to recover gracefully from this unhandled pointer reference, leading to a complete cessation of service for all queued and incoming print requests.\nThe attack is highly effective because it does not require authentication; the attacker only needs the ability to initiate an IPP print job request. The vulnerability is network-exposed, making any CUPS instance reachable by an untrusted network participant potentially susceptible to this DoS attack.\nWhile the current impact is identified primarily as a Denial of Service, the underlying nature of pointer dereference errors in daemon processes can sometimes be leveraged for further memory corruption, though the immediate result is process instability and downtime.\nThis vulnerability highlights a critical failure in the sanitization routines for job ticket metadata, where untrusted input is processed by privileged code without adequate boundary checking or sanity validation."
}