What’s Vulnerable › Vulnerabilities

CVE-2026-58122: Hermes WebUI < 0.51.307 Authentication Bypass via X-Forwarded-For Header Spoofing

• Severity: critical (CVSS 9.1 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.4% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-07-09 · updated 2026-10-25
• Weakness: CWE-348

Description

Hermes WebUI before 0.51.307 contains an authentication bypass vulnerability that allows unauthenticated remote attackers to circumvent local-origin IP restrictions on onboarding endpoints by supplying a spoofed X-Forwarded-For header with a loopback address. Attackers can exploit this bypass to perform server-side request forgery against internal services including cloud metadata endpoints, overwrite LLM provider configuration and API keys with attacker-controlled values, or initiate OAuth device-code flows to obtain persistent access tokens stored in auth.json.

Affected products

• nesquena hermes-webui: before 0.51.307 — fixed in 0.51.307

How to fix

Upgrade to a fixed version: nesquena hermes-webui 0.51.307. Check the vendor advisory for mitigations.

References

• https://github.com/nesquena/hermes-webui/commit/70596e6993be0d4cee083c1c1a86f5e7ad5d57b7
• https://github.com/nesquena/hermes-webui/pull/3758
• https://github.com/nesquena/hermes-webui/releases/tag/v0.51.307
• https://www.vulncheck.com/advisories/hermes-webui-authentication-bypass-via-x-forwarded-for-header-spoofing

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