EUVD-2026-76850
GHSA-c47m-m826-fc8g
Severity by source
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
AC:H reflects mandatory authorization code interception; S:C because attacker crosses trust boundary into victim's account scope.
Primary rating from Vendor (vulncheck).
CVSS VectorVendor: vulncheck
Lifecycle Timeline
5DescriptionCVE.org
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.
AnalysisAI
MCPHub's embedded OAuth 2.0 authorization server before v1.0.32 allows an attacker who intercepts a victim's authorization code to redeem it for valid access tokens without supplying a client secret or PKCE verifier. The root cause is a logic inversion in client authentication: the pre-fix condition checked if (clientSecret && client.clientSecret), meaning that omitting the secret in a token request caused the entire secret-validation block to be skipped, even for confidential clients with a registered secret. …
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Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata
Vulnerability AssessmentAI
| Exploitation | Exploitation requires three conditions to align: (1) MCPHub must have its embedded OAuth server enabled (oauthServer.enabled: true), which is a non-default configuration requiring explicit operator setup; (2) the attacker must obtain the short-lived authorization code issued to the victim, most feasibly via a network intercept on an unencrypted channel, a misconfigured or attacker-controlled redirect_uri, referrer-header leakage, or by registering a malicious client through the unauthenticated dynamic client registration endpoint if that feature is enabled; (3) a legitimate user must have initiated an authorization flow (UI:P). … Additional conditions and limiting factors are described in the full assessment. |
| Risk Assessment | The CVSS 4.0 score of 7.6 with AT:P (attack requires a specific precondition - authorization code interception) and UI:P (victim must initiate an OAuth flow) accurately constrains real-world exploitability relative to the VC:H/VI:H impact metrics. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in. |
| Exploit Scenario | Full exploit scenario with step-by-step reproduction available after sign-in. |
| Remediation | Upgrade MCPHub to v1.0.32 or later, which is the vendor-released patch available at https://github.com/samanhappy/mcphub/releases/tag/v1.0.32. … Detailed patch versions, workarounds, and compensating controls in full report. |
Recommended ActionAI
Within 24 hours, identify all MCPHub deployments and determine which are running versions before v1.0.32. …
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Same weakness CWE-287 – Improper Authentication
View allSame technique Authentication Bypass
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External POC / Exploit Code
Leaving vuln.today