CVE-2026-54603: OAuth2 is a Ruby wrapper for the OAuth 2.0 and 2.1 authorization frameworks, including OpenID Connect (OIDC)

This month

HIGH 8.6REMOTE

CVE-2026-54603 is a high-severity flaw (CVSS 8.6) affecting affected software. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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.

Why this priority

High severity
CISA SSVC: public proof of concept
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	8.6 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.4% (top 62%)
CISA exploited list	No
Weakness	CWE-200, CWE-601
Published	2026-07-28
Last modified	2026-10-23

Publisher (CNA): GitHub, Inc.

Timeline

2026-07-28 17:16 UTCPublished CVE record published
2026-10-23 23:10 UTCUpdated Record last modified

Exact fixes by distribution

RubyGems · oauth2 · FIXED · 2.0.22 · vulnerable: >= 0.4.0, <= 2.0.21 · source

bundle update oauth2 bundle list | grep oauth2

Fedora 46 · kwin-zones · FIXED · 1.0.13-1.fc46 · FEDORA-2026-95888f332b · source

sudo dnf upgrade --advisory=FEDORA-2026-95888f332b

Fedora ELN · nginx-mod-brotli · FIXED · 1.0.0~rc-16.eln159 · FEDORA-2026-501a6a8273 · source

sudo dnf upgrade --advisory=FEDORA-2026-501a6a8273

Debian 12 · ruby-oauth2 · FIXED · 1.4.4-1+deb12u1

sudo apt update && sudo apt install --only-upgrade ruby-oauth2 dpkg --compare-versions "$(dpkg-query -W -f='${Version}' ruby-oauth2)" ge "1.4.4-1+deb12u1" && echo PATCHED || echo STILL-VULNERABLE

Debian 13 · ruby-oauth2 · NO FIX YET

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

References

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