CVE-2026-90474 samanhappy CVE debrief

Who should care

Defenders responsible for MCPHub deployments should assess their exposure and prioritize patching to version 1.0.32 or later. This includes reviewing authentication configurations and monitoring for suspicious activity related to authorization codes and access tokens.

Why it matters

CVE-2026-90474 is an authentication bypass vulnerability in MCPHub's embedded OAuth 2.0 authorization server. Defenders should prioritize verifying the presence of MCPHub, assessing the current version, and applying the patch to prevent exploitation.

• Attackers may gain unauthorized access to victim accounts and their privileges.
• Defenders need to verify the presence of MCPHub in their environment and assess the current version.
• Defenders should apply the patch to version 1.0.32 or later to prevent exploitation.
• Defenders may need to review and update authentication configurations for the OAuth 2.0 authorization server.

Technical summary

The vulnerability is caused by client authentication being disabled by default and PKCE enforcement being optional in MCPHub's embedded OAuth 2.0 authorization server. This allows attackers to intercept authorization codes and redeem them for access tokens without providing a client secret or PKCE verifier. The issue impacts MCPHub deployments, which should be assessed for exposure and patched to version 1.0.32 or later. Defenders should review authentication configurations and monitor for suspicious activity related to authorization codes and access tokens.

Defensive priority

Defenders should prioritize verifying the presence of MCPHub in their environment, assessing the current version, and applying the patch to version 1.0.32 or later.

Recommended defensive actions

• Verify the presence of MCPHub in the environment and assess the current version.
• Apply the patch to version 1.0.32 or later.
• Review and update authentication configurations for the OAuth 2.0 authorization server.
• Monitor for suspicious activity related to authorization codes and access tokens.
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up.
• Plan vendor-supported updates or mitigations through normal change control where exposure is confirmed.
• Track exceptions, retest remediated assets, and close the item only after evidence is documented.

Evidence notes

The CVE record and NVD entry provide details on the vulnerability, including its CVSS score of 7.6 and HIGH severity. The vulnerability is described as an authentication bypass in MCPHub's OAuth 2.0 authorization server.

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.