GEM · JULY 2026 · EARLY WARNING

OAuth2 Gem Vulnerability: Bearer Token Leak via Protocol-Relative Redirect

EARLY WARNING · UNCONFIRMED. This page describes a developing threat that 0Day surfaced from early signals and has not yet independently confirmed. Details may change. Always verify against the primary sources before acting.
GHSA-PP92-CRG2-GFV9Severity: HIGH

An issue has been reported in the OAuth2 gem <=2.0.21 where the OAuth2::Client#request method may leak bearer tokens to an attacker host when a protocol-relative redirect is used.

What happened

An early warning has been issued regarding a potential vulnerability in the OAuth2 gem, specifically affecting versions up to and including 2.0.21. The issue reportedly involves the OAuth2::Client#request method, which may leak bearer tokens to an attacker host when a protocol-relative redirect is utilized. This vulnerability is under investigation, and it is recommended that users of the affected versions upgrade to a fixed version of the gem or apply a workaround if immediate upgrade is not feasible. For more detailed information, primary sources should be consulted.

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