CVE-2026-121640 in AuthPoint Authentication Gateway
Summary
by MITRE • 11/04/2026
An Authentication Bypass by Capture-replay vulnerability in WatchGuard AuthPoint Gateway allows an attacker who has observed a legitimate request between AuthPoint Gateway components to replay it and perform unauthorized administrative actions, including disrupting authentication services.
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Analysis
by VulDB Data Team • 11/04/2026
The identified vulnerability represents a critical failure in the integrity verification mechanisms of the WatchGuard AuthPoint Gateway architecture, specifically classified under Authentication Bypass by Capture-replay. This flaw allows an adversary who possesses network-level visibility into the communication channels between internal components to intercept valid requests and subsequently replay them to achieve unauthorized administrative control. The core technical deficiency lies in the absence or insufficiency of unique session identifiers, nonces, or cryptographic timestamps within the request payloads used for inter-component authentication. Without these dynamic elements, the system cannot distinguish between a fresh, legitimate command issued by an authorized administrator and a previously captured sequence that is being resent by an attacker. This lack of freshness validation effectively neutralizes standard replay protection measures such as one-time tokens or time-bound validity windows, rendering the internal trust model vulnerable to passive eavesdropping followed by active injection attacks.
From an operational perspective, the impact of this vulnerability extends beyond simple unauthorized access. An attacker who successfully exploits this flaw can perform administrative actions that compromise the entire multi-factor authentication infrastructure managed by AuthPoint Gateway. This includes disrupting critical authentication services, which could lead to a denial-of-service condition for legitimate users attempting to log in to protected resources. Furthermore, the ability to execute arbitrary administrative commands allows an adversary to modify security policies, disable monitoring features, or potentially escalate privileges within the broader network environment dependent on this gateway. The severity is amplified by the fact that internal component communication often traverses trusted networks where traditional perimeter defenses like firewalls may not inspect deep packet payloads for replay anomalies, assuming all traffic originates from verified sources.
This vulnerability aligns closely with Common Weakness Enumeration (CWE) identifiers such as CWE-294: Authentication Bypass by Capture-replay and CWE-384: Session Fixation, highlighting the fundamental design oversight in session management and request validation protocols. In terms of adversary tactics, this exploitation technique maps directly to MITRE ATT&CK techniques including T1076: Remote Desktop Protocol Replay Attack or more broadly T1557: Adversary-in-the-Middle if the attacker is positioned to intercept traffic, followed by T1098: Account Manipulation for administrative changes. The attack vector typically requires network access that allows sniffing of internal API calls or service-to-service communications, which may be achievable through compromised hosts on the same subnet or via man-in-the-middle positioning in unsegmented networks.
Mitigation strategies must focus on implementing robust cryptographic protections and strict validation logic within the gateway components. Immediate remediation involves ensuring all inter-component communication utilizes mutual TLS (mTLS) to encrypt traffic and authenticate both parties, thereby preventing passive eavesdropping. Additionally, developers should enforce the inclusion of unique request identifiers such as UUIDs or nonces in every API call, coupled with strict timestamp validation that rejects requests older than a minimal threshold, typically seconds. Implementing sequence numbers for ordered message processing can also prevent replay attacks by ensuring each subsequent command has a higher value than its predecessor. Organizations relying on this software should apply vendor-provided patches immediately and review network segmentation policies to isolate critical authentication infrastructure from general user networks, reducing the attack surface available for interception.