CVE-2026-8794 in PaperCut
Summary
by MITRE • 08/03/2026
PaperCut NG/MF contains an observable timing discrepancy in its authentication component. An unauthenticated remote attacker can exploit this vulnerability to perform username enumeration by measuring response times during login attempts. The system executes a password hash comparison only when a valid account is supplied, creating a measurable timing oracle that reveals account existence.
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Analysis
by VulDB Data Team • 08/03/2026
The vulnerability in PaperCut NG/MF represents a classic timing attack vector that exploits observable differences in system response times to infer information about user accounts. This weakness stems from the authentication mechanism's design where the system performs cryptographic password hash comparisons only when a valid username is provided, creating an exploitable timing oracle. The flaw directly aligns with common security vulnerabilities documented under CWE-347 and falls within the ATT&CK framework's credential access category, specifically targeting credential validation processes.
The technical implementation of this vulnerability allows attackers to measure response times during authentication attempts, distinguishing between valid and invalid account names through statistical analysis of system behavior. When an attacker submits a username that exists in the system, the application proceeds to perform the expensive cryptographic hash comparison operation, while invalid usernames trigger immediate rejection without executing these time-consuming operations. This differential execution time creates a measurable timing discrepancy that can be exploited to enumerate valid user accounts without requiring prior knowledge of credentials.
From an operational perspective, this vulnerability poses significant risk to organizations relying on PaperCut NG/MF for print management and authentication services. The remote nature of the attack means that threat actors can perform enumeration from any location without physical access to the system, making it particularly dangerous for environments where network exposure is high. Successful exploitation could lead to account takeover attempts, social engineering campaigns, or serve as a foundation for more sophisticated attacks targeting privileged accounts within the print management infrastructure.
The impact extends beyond simple account enumeration as this vulnerability can facilitate broader reconnaissance activities within the organization's authentication ecosystem. Attackers leveraging this timing discrepancy can build comprehensive user account dictionaries that may reveal organizational structures, identify high-value targets, and support subsequent phases of attack including password spraying or more targeted credential theft operations. Organizations utilizing PaperCut NG/MF should consider implementing rate limiting mechanisms and response time normalization to address this vulnerability while also applying the vendor-provided security patches as recommended in their official security advisories.
Mitigation strategies must focus on eliminating the timing oracle by ensuring consistent response times regardless of account validity during authentication attempts. This approach aligns with security best practices outlined in NIST SP 800-63B for authentication protocol design, which emphasizes the importance of constant-time operations to prevent information leakage through timing channels. Implementing cryptographic constant-time comparison functions and randomizing response delays can effectively neutralize this attack vector while maintaining system functionality and user experience. Organizations should also conduct regular security assessments to identify similar timing discrepancies in other authentication systems and ensure proper network segmentation to limit potential impact from successful exploitation attempts.