What is CVE-2026-54603?

CVE-2026-54603 is a high-severity vulnerability in Ruby-Oauth Oauth2, classified under Information Disclosure. CVSS score: 8.6/10. Published 2026-07-28.

How severe is CVE-2026-54603?

High severity. CVSS v3 base score is 8.6 out of 10.

Open Redirect in Ruby-Oauth Oauth2

CVE-2026-54603

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.

Vulnerability class: Information Disclosure

EPSS: 0.004 (36.6th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 8.6 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N.

Affected products

Ruby-oauth Oauth2 — versions >= 0.4.0, < 2.0.22

Weakness classification (CWE)

References

security-advisories@github.com (x_refsource_CONFIRM)
security-advisories@github.com (x_refsource_MISC)
security-advisories@github.com (x_refsource_MISC)

Frequently asked questions

What is CVE-2026-54603?: CVE-2026-54603 is a high-severity vulnerability in Ruby-Oauth Oauth2, classified under Information Disclosure. CVSS score: 8.6/10. Published 2026-07-28.
How severe is CVE-2026-54603?: High severity. CVSS v3 base score is 8.6 out of 10.