CVE-2026-58122
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…
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (0.37%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
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.
- CVSS 4.0
- 9.3 CRITICALCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/M
- EPSS
- 0.37% probability · 31th percentile
- CISA KEV
- Not listed
- Weakness
- CWE-348
- Source
- disclosure@vulncheck.com
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
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.