CVE-2026-108711

Plastic Labs Honcho through 3.3.0 contains an incorrect authorization vulnerability that allows peer- or session-scoped API key holders to read workspace data because get_or_create_workspace checks only the workspace claim. Attackers can submit their parent workspace name to the POST /v3/workspaces endpoint to retrieve workspace metadata and configuration, including custom_instructions, reserved for workspace or admin keys.

• https://github.com/plastic-labs/honcho
• https://github.com/plastic-labs/honcho/blob/608aec8a928da13c540262ed980c569448fb53ab/src/crud/workspace.py#L112-L119
• https://github.com/plastic-labs/honcho/blob/608aec8a928da13c540262ed980c569448fb53ab/src/routers/workspaces.py#L41-L72
• https://github.com/plastic-labs/honcho/blob/608aec8a928da13c540262ed980c569448fb53ab/src/security.py#L218-L225

• https://github.com/plastic-labs/honcho
• https://github.com/plastic-labs/honcho/blob/608aec8a928da13c540262ed980c569448fb53ab/src/crud/workspace.py#L112-L119
• https://github.com/plastic-labs/honcho/blob/608aec8a928da13c540262ed980c569448fb53ab/src/routers/workspaces.py#L41-L72
• https://github.com/plastic-labs/honcho/blob/608aec8a928da13c540262ed980c569448fb53ab/src/security.py#L218-L225
• https://hackmd.io/@haind/honcho-scoped-jwt-workspace-config-disclosure
• https://www.vulncheck.com/advisories/plastic-labs-honcho-through-3.3.0-incorrect-authorization-via-post-v3-workspaces

• HIGHCVE-2024-22031PoC
• MEDIUMCVE-2026-100259
• HIGHCVE-2026-100262
• LOWCVE-2026-100270
• HIGHCVE-2026-100273
• MEDIUMCVE-2026-100276
• HIGHCVE-2026-100277
• MEDIUMCVE-2026-100278

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