CVE-2026-49956: Hermes WebUI < 0.51.269 Profile Isolation Bypass via sessions search

Synopsis

An authentication bypass of profile isolation in Hermes WebUI (versions before 0.51.269) lets any logged-in user read session data belonging to other users' profiles by querying the sessions search endpoint, which fails to enforce active-profile filtering. The vulnerability is reachable over the network and requires only a low-privilege account; no special permissions or victim interaction are needed. Successful exploitation exposes session titles and transcript message content from profiles the attacker does not own. A patched-image rebuild at version 0.51.269 is available on HarborGuard for environments running an affected version.

HarborGuard Coverage

Exploit Conditions

• Network reachabilityRequired

  The attacker must reach the Hermes WebUI service over the network to send crafted requests to the sessions search endpoint.

• AuthenticationRequired

  Any low-privilege authenticated account is sufficient; no administrative or elevated permissions are needed.

• Victim interactionNot required

  The attacker sends requests directly to the endpoint; no action from another user is needed.

• Attack complexityDetail

  The exploit is reliable and condition-free; no race conditions or special environmental factors are required.

Blast Radius

• The attacker reads session titles from profiles other than their own active profile.
• The attacker reads full transcript message content from those foreign profiles, potentially exposing private conversations or sensitive data exchanged in other users' sessions.
• Confidentiality of all sessions indexed by the search endpoint is compromised for any authenticated user on the instance.