How to fix or mitigate CVE-2026-58122?

Within 24 hours: Inventory all Hermes WebUI deployments and determine current versions; immediately restrict network access to onboarding endpoints if running pre-0.51.307 instances. Within 7 days: Upgrade all instances to Hermes WebUI 0.51.307 or later and rotate all LLM API keys, OAuth tokens, and provider credentials stored in the platform. Within 30 days: Review authentication logs and auth.json files for evidence of compromise; audit and revoke any anomalous OAuth device tokens.

Hermes WebUI CVE-2026-58122

Q: What is the CVSS score of CVE-2026-58122?

CVE-2026-58122 has a CVSS 4.0 base score of 9.3 (Critical). CVSS vector: CVSS: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/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X. EPSS exploitation probability: 0.3%.

Q: Which versions of Hermes WebUI are affected by CVE-2026-58122?

Hermes WebUI versions before 0.51.307 contain a critical authentication bypass vulnerability that allows unauthenticated remote attackers to access restricted onboarding endpoints through HTTP header…. A patch is available.

EUVD-2026-42726 CRITICAL

Use of Less Trusted Source (CWE-348)

2026-07-09 VulnCheck

GHSA-rfj2-6v8r-3w64

Authentication Bypass SSRF Hermes Webui

9.3

CVSS 4.0 · Vendor: VulnCheck

Severity by source

Vendor (VulnCheck) PRIMARY

9.3 CRITICAL

CVSS: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/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

vuln.today AI

9.1 CRITICAL

Remote, unauthenticated, low-complexity header spoof (AV:N/AC:L/PR:N/UI:N) yielding SSRF/credential disclosure (C:H) and config/key overwrite (I:H) with no availability loss (A:N).

3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

4.0 AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N

Primary rating from Vendor (VulnCheck).

CVSS VectorVendor: VulnCheck

CVSS: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/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Lifecycle Timeline

Analysis Generated

Jul 09, 2026 - 22:09 vuln.today

DescriptionCVE.org

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.

AnalysisAI

Authentication bypass in Hermes WebUI before 0.51.307 lets unauthenticated remote attackers reach onboarding endpoints that are supposed to be restricted to loopback traffic by spoofing an X-Forwarded-For header with a 127.0.0.1 value. Once past the origin check, an attacker can pivot to server-side request forgery against internal services and cloud metadata endpoints, overwrite LLM provider configuration and API keys, or start an OAuth device-code flow to mint persistent tokens saved in auth.json. A vendor patch exists; the flaw carries a CVSS 4.0 score of 9.3, but no public exploit code has been identified at time of analysis.

Technical ContextAI

Hermes WebUI is a self-hosted web interface (GitHub project nesquena/hermes-webui, CPE cpe:2.3:a:nesquena:hermes-webui) for managing LLM providers and their credentials. To protect sensitive first-run onboarding routes, it gates them to local-origin requests - but it trusts the client-supplied X-Forwarded-For header to determine the source IP instead of the actual TCP peer address. This is the root cause captured by CWE-348 (Use of Less Trusted Source): a security decision (is this request local?) is made from attacker-controllable input. Because X-Forwarded-For is a plain request header, any remote client can assert a loopback address and satisfy the check, exposing endpoints that perform outbound fetches (SSRF sink reaching cloud metadata such as 169.254.169.254), mutate provider config/API keys, and drive OAuth device-code token issuance.

RemediationAI

Vendor-released patch: upgrade to Hermes WebUI v0.51.307 or later, which is the primary and complete fix (release: https://github.com/nesquena/hermes-webui/releases/tag/v0.51.307; fix PR https://github.com/nesquena/hermes-webui/pull/3758; patch commit https://github.com/nesquena/hermes-webui/commit/70596e6993be0d4cee083c1c1a86f5e7ad5d57b7). If you cannot upgrade immediately, do not expose the service to untrusted networks: bind it to localhost or place it behind a reverse proxy that strips or overrides inbound X-Forwarded-For headers so clients cannot forge the source IP (side effect - you must then configure the proxy as the sole trusted hop, or legitimate remote access breaks). Additionally restrict network access to the onboarding endpoints via firewall/ACL and rotate any LLM provider API keys and OAuth tokens (auth.json) that may have been exposed or overwritten. Consult the VulnCheck advisory (https://www.vulncheck.com/advisories/hermes-webui-authentication-bypass-via-x-forwarded-for-header-spoofing) for full details.