What’s Vulnerable › Vulnerabilities

CVE-2026-55198: Hermes WebUI < 0.51.443 - Cross-Profile Session Data Exfiltration via Session Export Endpoint

• Severity: medium (CVSS 6.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.3% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-06-17 · updated 2026-10-26
• Weakness: CWE-639

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.

Affected products

• nesquena hermes-webui: before 0.51.443 — fixed in 0.51.443

How to fix

Upgrade to a fixed version: nesquena hermes-webui 0.51.443. Check the vendor advisory for mitigations.

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

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