What’s Vulnerable › Vulnerabilities

CVE-2026-54603: OAuth2::Client#request: Protocol-relative redirect Location overrides authority, leaking bearer Authorization to attacker host

• Severity: high (CVSS 8.6 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.4% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-07-28 · updated 2026-10-23
• Weakness: CWE-200

Description

OAuth2 is a Ruby wrapper for the OAuth 2.0 and 2.1 authorization frameworks, including OpenID Connect (OIDC). From 0.4.0 to 2.0.21, a protocol-relative redirect Location returned to OAuth2::Client#request overrides the request authority, so the bearer Authorization header is sent to an attacker-controlled host, leaking the credential. This issue is fixed in version 2.0.22.

Affected products

• ruby-oauth oauth2: from 0.4.0, < 2.0.22

References

• https://github.com/ruby-oauth/oauth2/commit/0f0a474f1b38453e119e660c2daca742d4378ce9
• https://github.com/ruby-oauth/oauth2/releases/tag/v2.0.22
• https://github.com/ruby-oauth/oauth2/security/advisories/GHSA-pp92-crg2-gfv9
• https://lists.debian.org/debian-lts-announce/2026/10/msg00014.html
• https://github.com/ruby-oauth/oauth2/security/advisories/GHSA-pp92-crg2-gfv9

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