CVE-2026-4924: Devolutions Server 2FA Bypass Vulnerability

CVE-2026-4924 Overview

CVE-2026-4924 is an authentication bypass vulnerability affecting the two-factor authentication (2FA) feature in Devolutions Server 2026.1.11 and earlier versions. This improper authentication flaw allows a remote attacker who has obtained valid credentials to bypass the multifactor authentication mechanism by reusing a partially authenticated session token, ultimately gaining unauthorized access to victim accounts.

Critical Impact

Attackers with valid credentials can completely bypass 2FA protections to gain full access to user accounts, undermining the security benefits of multifactor authentication and potentially exposing sensitive credential vaults and enterprise secrets.

Affected Products

• Devolutions Server 2026.1.11 and earlier versions
• Devolutions Server installations with 2FA enabled

Discovery Timeline

• April 1, 2026 - CVE-2026-4924 published to NVD
• April 1, 2026 - Last updated in NVD database

Technical Details for CVE-2026-4924

Vulnerability Analysis

This vulnerability is classified under CWE-1390 (Weak Authentication), indicating a fundamental flaw in how the authentication system validates user sessions during the two-factor authentication process. The core issue lies in the improper handling of partially authenticated session tokens, which can be captured and reused to bypass the second authentication factor entirely.

When a user initiates the login process with valid primary credentials, the system generates a session token to track the authentication state. However, due to insufficient validation, this partially authenticated token can be extracted and replayed, allowing an attacker to skip the 2FA verification step. This defeats the purpose of implementing multifactor authentication, as the additional security layer can be circumvented through session token manipulation.

The attack requires network access and valid user credentials, but the ability to bypass 2FA significantly elevates the risk, especially in enterprise environments where Devolutions Server manages sensitive credentials and secrets.

Root Cause

The root cause stems from improper session state management during the multi-step authentication workflow. The application fails to properly invalidate or restrict the use of session tokens that have only completed the first factor of authentication. This allows the token to be reused in a context where 2FA verification should be enforced but is not adequately validated before granting access.

Attack Vector

The attack is conducted remotely over the network. An attacker must first obtain valid user credentials through methods such as phishing, credential stuffing, or data breaches. Once credentials are obtained, the attacker initiates a login attempt and captures the partially authenticated session token generated after successful password verification. This token can then be manipulated or replayed to bypass the 2FA challenge, granting unauthorized access to the target account without completing the second authentication factor.

The vulnerability mechanism involves intercepting the authentication flow after the first factor succeeds but before 2FA completion. The session token at this intermediate state does not have adequate protections to prevent reuse or bypass. Technical details regarding the specific exploitation methodology can be found in the Devolutions Security Advisory.

Detection Methods for CVE-2026-4924

Indicators of Compromise

• Multiple failed 2FA attempts followed by successful logins without completed 2FA verification
• Session tokens being used from different IP addresses or geographic locations in rapid succession
• Authentication logs showing successful password verification without corresponding 2FA completion events
• Unusual patterns of account access immediately following partial authentication attempts

Detection Strategies

• Implement correlation rules to detect successful logins where 2FA verification events are missing from audit logs
• Monitor for session token reuse patterns across multiple requests or from disparate network locations
• Enable enhanced logging for authentication events to capture the full authentication workflow state
• Deploy behavioral analytics to identify accounts with anomalous login patterns indicating 2FA bypass

Monitoring Recommendations

• Enable verbose authentication logging in Devolutions Server to capture all authentication state transitions
• Configure alerts for accounts accessing sensitive vaults without complete 2FA verification trails
• Monitor network traffic for suspicious authentication API calls that skip expected verification steps
• Review authentication audit logs regularly for signs of session manipulation or replay attacks

How to Mitigate CVE-2026-4924

Immediate Actions Required

• Upgrade Devolutions Server to a patched version that addresses the authentication bypass vulnerability
• Review recent authentication logs for any signs of exploitation or unauthorized access
• Force password resets for accounts that may have been compromised through credential exposure
• Implement additional network-layer security controls to restrict access to the authentication endpoints

Patch Information

Devolutions has released a security advisory addressing this vulnerability. Organizations should consult the Devolutions Security Advisory DEVO-2026-0010 for detailed patching instructions and the recommended upgrade path. Ensure all Devolutions Server instances are updated beyond version 2026.1.11 to remediate this vulnerability.

Workarounds

• Restrict network access to Devolutions Server using firewall rules or VPN requirements to limit the attack surface
• Implement IP-based access restrictions to only allow authentication from known corporate networks
• Enable session binding to enforce single-use session tokens that cannot be replayed
• Deploy a web application firewall (WAF) with rules to detect and block authentication anomalies

Configuration changes should be applied following Devolutions documentation. Consult the Devolutions Security Advisory for specific mitigation guidance and configuration recommendations tailored to your deployment.