CVE-2026-100868 Penpot before 2.18.0 Unauthenticated WebSocket Access via MCP Bridge
Unauthenticated attackers can access the MCP WebSocket bridge in single-user mode to intercept and forge task payloads.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-100868?
CVE-2026-100868 is a medium-severity missing authorization vulnerability in @penpot/mcp, published on 27 Sep 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
Penpot before 2.18.0 binds the MCP server plugin WebSocket bridge to all network interfaces without authentication in single-user mode. Unauthenticated attackers on adjacent networks can connect to the WebSocket port to impersonate the Penpot browser plugin, intercept task payloads, and return forged results to the MCP client.
Weakness: CWE-1327
Which versions are affected by CVE-2026-100868?
How do I fix CVE-2026-100868?
No fix has been published for CVE-2026-100868 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-2026-100868 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-100868 exists.
Sources
Also known as GHSA-hm3w-7xgf-hfwf.