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Vulnerability record · CVE-2026-55197 · published 17 June 2026

CVE-2026-55197: Insecure direct object reference vulnerability

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.

7.1 CVSS 4.0 High EPSS 0.47% · top 61.5% CWE-639 · Insecure direct object reference Deferred
7.1CVSS 4.0 base score
0.47%EPSS exploitation probability, 30 days
NoNot in CISA KEV
0Affected product versions listed by NVD
6References
17 Sep 2026Last modified by NVD

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.

CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:N/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:

References

LinkTags
https://github.com/nesquena/hermes-webui/commit/2a3baa71b81ca92da8ece8616a09f15894beec71
https://github.com/nesquena/hermes-webui/pull/3982
https://github.com/nesquena/hermes-webui/pull/4269
https://github.com/nesquena/hermes-webui/releases/tag/v0.51.443
https://www.vulncheck.com/advisories/hermes-webui-broken-access-control-in-api-session-endpoint
https://github.com/nesquena/hermes-webui/pull/3982

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

8.4CVE-2026-55255Langflow IDOR in responses endpoint allows cross-user flow executionLangflow before 1.9.1 has an insecure direct object reference in the /api/v1/responses endpoint. An authenticated attacker can supply another user's …KEVEPSS 0.89%analysed

Source: NIST National Vulnerability Database (record CVE-2026-55197), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.