Home

Description

Hermes WebUI before 0.51.443 contains a broken access control vulnerability in the /api/session endpoint that allows authenticated users to disclose cross-profile session transcripts. Attackers can bypass profile boundary checks by directly querying session IDs belonging to other profiles via GET /api/session?session_id=<foreign_id>&messages=1 to retrieve unauthorized conversation transcripts and metadata.

PUBLISHED Reserved 2026-06-16 | Published 2026-06-17 | Updated 2026-06-17 | Assigner VulnCheck




HIGH: 7.1CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N

MEDIUM: 6.5CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N

Problem types

Authorization Bypass Through User-Controlled Key

Product status

Default status
unaffected

Any version before 0.51.443
affected

0.51.443 (semver)
unaffected

Credits

Chia Min Jun Lennon finder

References

github.com/nesquena/hermes-webui/pull/3982 exploit

github.com/nesquena/hermes-webui/releases/tag/v0.51.443 (Release Notes) release-notes

github.com/nesquena/hermes-webui/pull/3982 (Researcher Pull Request) technical-description

github.com/nesquena/hermes-webui/pull/4269 (Maintainer Pull Request) issue-tracking

github.com/...ommit/2a3baa71b81ca92da8ece8616a09f15894beec71 (Patch Commit) patch

www.vulncheck.com/...-access-control-in-api-session-endpoint third-party-advisory

cve.org (CVE-2026-55197)

nvd.nist.gov (CVE-2026-55197)

Download JSON