CVE-2026-63089 in WireGuard Easy
Summary
by MITRE • 07/16/2026
WireGuard Easy through 15.3.0, fixed in commit 66b292b, contains a cryptographically weak one-time link token generation vulnerability that allows unauthenticated network attackers to recover WireGuard peer credentials by brute-forcing a keyspace of at most 1000 candidate tokens per client ID, as the token is computed using CRC32 over a random value constrained to 0-999. Attackers can enumerate candidate tokens against the unauthenticated /cnf/:oneTimeLink route, which lacks rate limiting and does not validate token expiration, to obtain a peer's PrivateKey and PresharedKey and impersonate that peer on the VPN network.
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Analysis
by VulDB Data Team • 07/16/2026
WireGuard Easy version 15.3.0 and earlier contains a critical cryptographic weakness in its one-time link token generation mechanism that fundamentally undermines the security of the VPN infrastructure. This vulnerability stems from the implementation of a cryptographically insecure random number generator where tokens are derived using CRC32 over a random value constrained to a range of 0-999, creating a manageable keyspace of at most 1000 candidate tokens per client ID. The flaw represents a direct violation of cryptographic best practices and aligns with CWE-330, which addresses the use of weak randomness in security-critical applications. The vulnerability exists within the /cnf/:oneTimeLink endpoint, which serves as an unauthenticated access point for credential retrieval without proper rate limiting or token expiration validation mechanisms.
The operational impact of this vulnerability is severe and directly enables man-in-the-middle attacks against WireGuard VPN networks. Attackers can systematically enumerate candidate tokens against the vulnerable endpoint, exploiting the limited keyspace to recover valid peer credentials including PrivateKey and PresharedKey values. This compromise allows unauthorized parties to impersonate legitimate VPN peers and gain persistent access to network resources without requiring authentication. The attack vector specifically targets the configuration endpoint that should remain protected from unauthenticated access, creating a direct pathway for attackers to establish malicious connections within the VPN infrastructure. The absence of rate limiting mechanisms on this endpoint makes the brute force attack highly efficient and minimally detectable.
Security controls fail entirely at multiple layers in this scenario, representing a fundamental breakdown in authentication and authorization mechanisms that aligns with ATT&CK technique T1078.004 for Valid Accounts and T1566.002 for Phishing. The vulnerability enables attackers to bypass traditional network security measures by leveraging legitimate access points within the VPN configuration framework. Network defenders lose visibility into malicious credential usage because the attack occurs through legitimate API endpoints designed for authorized access. The cryptographic weakness directly impacts the confidentiality and integrity of the entire VPN ecosystem, as compromised peer credentials can be used to decrypt communications and establish unauthorized network connections. This vulnerability demonstrates how insufficient entropy in security token generation can completely undermine the security model of a network infrastructure.
The remediation approach must address both immediate operational concerns and fundamental architectural flaws in the token generation system. The fix implemented in commit 66b292b should replace the CRC32-based token generation with cryptographically secure random number generation that produces tokens with sufficient entropy to prevent brute force attacks. Additionally, rate limiting mechanisms must be implemented at the /cnf/:oneTimeLink endpoint to prevent automated enumeration attempts, while proper token expiration validation should be enforced to limit the window of opportunity for attackers. Organizations should consider implementing multi-factor authentication controls and monitoring for unusual access patterns to detect potential exploitation attempts. The incident highlights the critical importance of secure random number generation in security-sensitive applications and the necessity of applying defense-in-depth principles even at network configuration endpoints that appear to provide limited access.