Guzzle OAuth Subscriber has insufficient nonce entropy (CVE-2025-21617)
The Guzzle OAuth Subscriber before version 0.8.1 generates nonces with insufficient entropy using a non-cryptographically secure pseudorandom source. This weakness can expose servers to replay attacks if TLS is not employed. No workarounds are available. Users should upgrade to version 0.8.1 or later to address this issue.
AI Analysis
Technical Summary
This vulnerability in guzzlehttp/oauth-subscriber (CVE-2025-21617) involves insufficient entropy in nonce generation, specifically the use of a non-cryptographically secure pseudorandom source. This flaw can allow replay attacks against servers that do not use TLS. The issue is fixed by upgrading to version 0.8.1 or higher. No alternative mitigations or workarounds exist.
Potential Impact
Servers using affected versions of guzzlehttp/oauth-subscriber without TLS protection may be vulnerable to replay attacks due to predictable nonce values. This could allow attackers to reuse intercepted requests, potentially leading to unauthorized actions or session hijacking in environments lacking transport encryption.
Mitigation Recommendations
Upgrade guzzlehttp/oauth-subscriber to version 0.8.1 or later. No workarounds are available. Applying the official fix eliminates the insufficient entropy issue in nonce generation.
Guzzle OAuth Subscriber has insufficient nonce entropy (CVE-2025-21617)
Description
The Guzzle OAuth Subscriber before version 0.8.1 generates nonces with insufficient entropy using a non-cryptographically secure pseudorandom source. This weakness can expose servers to replay attacks if TLS is not employed. No workarounds are available. Users should upgrade to version 0.8.1 or later to address this issue.
CVSS v4.0
Affected software
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Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
This vulnerability in guzzlehttp/oauth-subscriber (CVE-2025-21617) involves insufficient entropy in nonce generation, specifically the use of a non-cryptographically secure pseudorandom source. This flaw can allow replay attacks against servers that do not use TLS. The issue is fixed by upgrading to version 0.8.1 or higher. No alternative mitigations or workarounds exist.
Potential Impact
Servers using affected versions of guzzlehttp/oauth-subscriber without TLS protection may be vulnerable to replay attacks due to predictable nonce values. This could allow attackers to reuse intercepted requests, potentially leading to unauthorized actions or session hijacking in environments lacking transport encryption.
Mitigation Recommendations
Upgrade guzzlehttp/oauth-subscriber to version 0.8.1 or later. No workarounds are available. Applying the official fix eliminates the insufficient entropy issue in nonce generation.
Technical Details
- Gcve Source
- db.gcve.eu
- Osv Id
- GHSA-237r-r8m4-4q88
- Osv Schema Version
- 1.4.0
- Aliases
- ["CVE-2025-21617"]
- Ecosystems
- ["Packagist"]
- Database Specific Severity
- MODERATE
- Cvss Version
- 4.0
Threat ID: 6a58b41468715ace43d6831e
Added to database: 07/16/2026, 10:36:04 UTC
Last enriched: 07/16/2026, 10:56:13 UTC
Last updated: 09/10/2026, 19:36:49 UTC
Views: 30
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