CVE-2026-10224

Vulnerability

The vulnerability resides in the _handle_webhook_request function in gateway/platforms/feishu.py of NousResearch hermes-agent up to version 2026.4.30. The rate-limiting check is performed before verification token and signature validation, meaning any request—even those with invalid signatures—increments the same per-source rate-limit bucket keyed by (app_id, webhook_path, remote_ip). This design flaw allows unauthenticated traffic to exhaust the bucket. [1]

Exploitation

An attacker can remotely send repeated webhook requests with invalid signatures without any authentication. Each request consumes the shared rate-limit bucket. Once the bucket is exhausted, subsequent legitimate signed webhook requests from the same source IP are rejected with an HTTP 429 status. A public proof-of-concept exploit script is available. [1]

Impact

Successful exploitation results in denial of service: valid webhook deliveries are blocked, preventing the application from processing legitimate events. No data confidentiality or integrity is compromised, but availability is degraded. The attacker does not gain any privileged access. [1]

Mitigation

As of the publication date, the vendor has not responded and no official patch has been released. Users can mitigate by implementing additional rate limiting or authentication checks before the existing rate limiter, or by restricting access to the webhook endpoint to trusted IP addresses. [1]