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Description

Hermes WebUI before 0.51.443 contains an authorization bypass vulnerability in the session export endpoint that allows authenticated users to access sessions from other profiles. The _handle_session_export handler in api/routes.py fails to verify active-profile ownership before serializing session data, enabling attackers to exfiltrate foreign session transcripts by guessing or knowing session identifiers.

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/3991 exploit

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

github.com/nesquena/hermes-webui/pull/3991 (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/...xfiltration-via-session-export-endpoint third-party-advisory

cve.org (CVE-2026-55198)

nvd.nist.gov (CVE-2026-55198)

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