CVE-2025-21617 in oauth-subscriber
Summary
by MITRE • 01/06/2025
Guzzle OAuth Subscriber signs Guzzle requests using OAuth 1.0. Prior to 0.8.1, Nonce generation does not use sufficient entropy nor a cryptographically secure pseudorandom source. This can leave servers vulnerable to replay attacks when TLS is not used. This vulnerability is fixed in 0.8.1.
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Analysis
by VulDB Data Team • 01/06/2025
The vulnerability identified as CVE-2025-21617 affects the Guzzle OAuth Subscriber component within the Guzzle HTTP client library. This issue specifically targets the implementation of OAuth 1.0 authentication mechanisms where the nonce generation process fails to utilize adequate entropy sources. The weakness lies in the cryptographic implementation where the random number generation does not meet modern security standards for generating secure nonces. The vulnerability exists in versions prior to 081 and represents a significant concern for systems relying on OAuth 1.0 authentication without additional transport layer security measures.
The technical flaw manifests in the insufficient entropy of nonce generation which directly impacts the security guarantees of OAuth 1.0 protocol implementation. A nonce in OAuth 1.0 serves as a unique value that prevents replay attacks by ensuring that each request is unique and cannot be reused by an attacker. When the nonce generation does not employ cryptographically secure pseudorandom number generators, attackers can potentially predict or reuse nonces, thereby compromising the authentication mechanism. This vulnerability falls under the CWE-330 category of insufficient entropy, which is classified as a weakness that can lead to predictable random values and subsequent security breaches.
The operational impact of this vulnerability becomes particularly severe when systems operate without Transport Layer Security such as TLS. Without encrypted communication channels, the predictable nonce values can be intercepted and reused by malicious actors to perform replay attacks against the authenticated services. This creates a scenario where an attacker can capture a valid OAuth request and replay it multiple times, potentially gaining unauthorized access to protected resources or performing unauthorized operations on behalf of legitimate users. The risk is amplified in environments where sensitive data is transmitted over unencrypted connections, making the attack surface significantly larger.
The mitigation for this vulnerability requires immediate upgrading to version 0.8.1 or later of the Guzzle OAuth Subscriber component where the nonce generation has been properly implemented using cryptographically secure random number generation methods. Organizations should also ensure that all systems utilizing OAuth 1.0 authentication implement mandatory TLS encryption for all communications. Security teams should conduct thorough assessments of their OAuth implementations to identify any other potential weaknesses in their authentication frameworks. The fix addresses the core cryptographic weakness by ensuring that all nonce values are generated using proper entropy sources that meet industry standards for cryptographic security.
This vulnerability aligns with several ATT&CK framework techniques including T1566 for credential access through replay attacks and T1071 for application layer protocols that may be exploited. The remediation process should include not only updating the library but also implementing proper monitoring for suspicious authentication patterns that could indicate replay attack attempts. Organizations should also consider implementing additional authentication layers or transitioning to OAuth 2.0 which provides better security guarantees and more robust cryptographic implementations. The vulnerability demonstrates the critical importance of proper cryptographic implementation in security-sensitive components and highlights the need for continuous security auditing of third-party libraries used in production systems.