APIFold constructs an MCP server from an OpenAPI or Swagger specification and exposes the endpoint /webhooks/:serverSlug/:eventName. Prior to a specific commit, the handler accepts any JSON payload without performing signature validation or authentication, storing the data in Redis and a PostgreSQL table as if it had been generated by a legitimate client. This omission allows an attacker to craft and submit arbitrary event data that the server trusts, potentially altering configuration, triggering unintended actions, or revealing sensitive information. The vulnerability is rooted in the absence of authentication checks (CWE‑306).

All installations of Work90210:APIFold deployed with a version or commit before 7f19b52280f414f57af2b79a95333d1c8fbeece5 are affected. The exact range of prior versions is unspecified, but any instance that generated its webhook router using the unpatched code path is vulnerable. No specific version numbers are listed in the advisory.

The CVSS score of 5.3 indicates a moderate severity. The EPSS score of less than 1% suggests that exploitation is currently rare, and the vulnerability is not reported in CISA's KEV catalog. The likely attack vector is an unauthenticated HTTP request to the webhook endpoint; exploitation requires knowledge of a valid server slug but no additional privileges. Because the payload is stored directly and later served to legitimate clients, an attacker can effectively impersonate a trusted event source. While the low EPSS implies limited current active exploitation, the potential impact justifies prompt remediation.