CVE-2026-90474: Auth Bypass (CVSS 6.8)

Description

MCPHub before 1.0.32 contains an authentication bypass vulnerability in its embedded OAuth 2.0 authorization server where client authentication is disabled by default and PKCE enforcement is optional. Attackers who obtain an authorization code through interception can redeem it for access tokens without providing a client secret or PKCE verifier, gaining access to victim accounts and their privileges.

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CVSS v3.1 Score

6.8

MEDIUM

CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:N

EPSS — Exploit Prediction

0.0030

Probability of exploitation

0.23%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-287 Improper Authentication

References

Other References

https://github.com/samanhappy/mcphub/blob/v1.0.31/src/services/oauthServerService.ts#L26-L38 https://github.com/samanhappy/mcphub/commit/e927620cd1a80e8691213b01eb8cd6ffa1a66e9f https://github.com/samanhappy/mcphub/releases/tag/v1.0.32 https://github.com/samanhappy/mcphub/security/advisories/GHSA-3m7m-37xf-xp9x https://www.vulncheck.com/advisories/mcphub-before-1.0.32-oauth-2.0-authentication-bypass https://github.com/samanhappy/mcphub/security/advisories/GHSA-3m7m-37xf-xp9x

Frequently Asked Questions

What is CVE-2026-90474? +

MCPHub before 1.0.32 contains an authentication bypass vulnerability in its embedded OAuth 2.0 authorization server where client authentication is disabled by default and PKCE enforcement is optional. Attackers who obtain an authorization code through interception can redeem it for access tokens without providing a client secret or PKCE verifier, gaining access to victim accounts and their privileges. It has a CVSS v3.1 base score of 6.8 (MEDIUM).

How severe is CVE-2026-90474? +

CVE-2026-90474 has a CVSS v3.1 score of 6.8 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance. The EPSS score is 0.0030, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-90474? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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