CVE-2026-55197 Hermes WebUI < 0.51.443 - Broken Access Control in /api/session Endpoint
Authenticated users can bypass profile boundaries to read other users' session transcripts and metadata via the /api/session endpoint.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-55197?
CVE-2026-55197 is a high-severity missing authorization vulnerability in nesquena hermes-webui, published on 17 Jun 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official 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.
Weakness: CWE-639
Which versions are affected by CVE-2026-55197?
How do I fix CVE-2026-55197?
No fix has been published for CVE-2026-55197 yet. Limit exposure of the affected software until one is available.
Upgrade, and check permissions on every request on the server, not only in the interface. More about Missing authorization.
Is CVE-2026-55197 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-55197 exists.
Sources
Also known as GHSA-5wqv-fhmr-pjgh.