CVE-2026-55198 Hermes WebUI < 0.51.443 - Cross-Profile Session Data Exfiltration via Session Export Endpoint
Authenticated users can exfiltrate session data from other profiles due to missing ownership checks in the session export 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-2026-55198?
CVE-2026-55198 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 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.
Weakness: CWE-639
Which versions are affected by CVE-2026-55198?
How do I fix CVE-2026-55198?
No fix has been published for CVE-2026-55198 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-2026-55198 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-55198 exists.
Sources
Also known as GHSA-34j3-4jpj-gx6q.