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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.

PUBLISHED Reserved 2026-06-29 | Published 2026-07-09 | Updated 2026-07-14 | Assigner VulnCheck




CRITICAL: 9.3CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N

CRITICAL: 9.1CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

Problem types

Use of Less Trusted Source

Product status

Default status
affected

Any version before 0.51.307
affected

Credits

fantasticsquirrel finder

References

github.com/nesquena/hermes-webui/releases/tag/v0.51.307 (Release Notes) release-notes

github.com/nesquena/hermes-webui/pull/3758 (Pull Request) issue-tracking

github.com/...ommit/70596e6993be0d4cee083c1c1a86f5e7ad5d57b7 (Patch Commit) patch

www.vulncheck.com/...ass-via-x-forwarded-for-header-spoofing third-party-advisory

cve.org (CVE-2026-58122)

nvd.nist.gov (CVE-2026-58122)

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