6.5Medium
CVE-2026-55198
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.
What this means for your business
- An attacker can use it remotely, over a network, with an ordinary user login, and without anyone at your company clicking anything.
- FIRST's prediction model gives it a 0.3% chance of attack attempts being seen in the next 30 days, ranking above 19% of all known flaws.
What to do
- 1Ask your IT team or provider whether any of your systems use the affected product.
- 2If you do, follow the vendor's guidance. No patch reference has been published yet.
Not sure if your company is exposed?
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Scoring
- CVSS
- 6.5 (v3.1)
- Vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N- CVSS v4
- 7.1
- Weakness
- CWE-639
- Assigned by
- disclosure@vulncheck.com
Dates
- Published
- 2026-06-17
- Last modified
- 2026-09-17
- Sources
- NVD
References
- https://github.com/nesquena/hermes-webui/commit/2a3baa71b81ca92da8ece8616a09f15894beec71
- https://github.com/nesquena/hermes-webui/pull/3991
- 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-cross-profile-session-data-exfiltration-via-session-export-endpoint
- https://github.com/nesquena/hermes-webui/pull/3991