CVE-2026-61503 in HFS
Summary
by MITRE • 07/13/2026
Rejetto HFS 3.0.0 through 3.2.0 returns observably different responses from its login endpoint depending on whether the submitted username exists. A remote unauthenticated attacker can use this to confirm valid account names, including the default admin account, facilitating password-guessing and session-forgery attacks.
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Analysis
by VulDB Data Team • 07/13/2026
This vulnerability in Rejetto HFS versions 3.0.0 through 3.2.0 represents a classic information disclosure weakness that fundamentally undermines authentication security mechanisms. The flaw manifests as observable response differences from the login endpoint when processing valid versus invalid usernames, creating a timing-based side-channel attack vector that exposes account existence information without requiring authentication credentials. This behavior directly violates secure coding principles that mandate consistent response handling regardless of input validation outcomes.
The technical implementation of this vulnerability stems from improper error handling within the authentication routine where the system differentiates between nonexistent accounts and incorrect passwords through varying response times or content structures. Attackers can exploit this inconsistency to enumerate valid user accounts, particularly targeting default administrative accounts that are commonly known and frequently targeted in automated attack campaigns. This type of vulnerability maps directly to CWE-204, which addresses information exposure through response differences, and aligns with ATT&CK technique T1110.003 for credential stuffing attacks.
The operational impact extends beyond simple account enumeration, as this vulnerability creates a foundation for more sophisticated attacks including password-guessing campaigns, session forgery attempts, and brute force operations that can bypass authentication mechanisms entirely. Remote unauthenticated attackers can systematically test username combinations to identify valid accounts within the system, significantly reducing the complexity of subsequent exploitation phases. The vulnerability affects organizations running affected versions of Rejetto HFS, particularly those with default installations or weak password policies that may be exploited through automated tools.
Mitigation strategies must address both immediate patching requirements and defensive configurations to prevent similar issues in future deployments. Organizations should immediately upgrade to patched versions of Rejetto HFS that implement consistent error handling for authentication endpoints. Additionally, implementing rate limiting mechanisms at network boundaries, employing strong authentication policies with multi-factor authentication, and configuring intrusion detection systems to monitor for account enumeration attempts can provide layered defense against exploitation. Security configurations should enforce uniform response timing regardless of account validity to eliminate side-channel information leakage. Network segmentation and access control measures should be implemented to reduce the attack surface available to remote threat actors attempting credential-based attacks against vulnerable systems.