Hermes WebUI Authentication Bypass Vulnerability Reported
An early warning has been issued regarding a critical vulnerability in Hermes WebUI versions prior to 0.51.307. This vulnerability, tracked as CVE-2026-58122, reportedly allows unauthenticated remote attackers to bypass local-origin IP restrictions on onboarding endpoints, potentially leading to server-side request forgery against internal services.
What happened
Hermes WebUI before version 0.51.307 is under investigation for containing an authentication bypass vulnerability. This vulnerability appears to allow unauthenticated remote attackers to circumvent local-origin IP restrictions on onboarding endpoints by supplying a spoofed X-Forwarded-For header with a loopback address. Exploiting this bypass, attackers may perform server-side request forgery against internal services, including cloud metadata endpoints.
The potential impact of this vulnerability includes the overwrite of LLM provider configuration and API keys with attacker-controlled values, as well as the initiation of OAuth device-code flows to obtain persistent access tokens stored in auth.json. The CVSS score for this vulnerability is 9.1, indicating a critical severity level.
To assess your exposure, check if your deployment includes Hermes WebUI versions prior to 0.51.307. It is recommended to upgrade to version 0.51.307 or later to mitigate the vulnerability. For more detailed information, consult the primary sources linked in the threat data.
How 0Day mitigates this
hermes-webui is anywhere in your dependency tree, the engineers who own the affected repositories get a push alert the moment it is flagged — no manual audit to remember to run.Read how this differs from waiting on a scanner to catch a known advisory, or see the exact, read-only access 0Day needs to do this for an organization.