CVE-2026-100868
Penpot before 2.18.0 Unauthenticated WebSocket Access via MCP Bridge
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.
INFO
Published Date :
Sept. 27, 2026, 1:16 p.m.
Last Modified :
Sept. 27, 2026, 1:16 p.m.
Remotely Exploit :
No
Source :
[email protected]
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS 3.1 | MEDIUM | 83251b91-4cc7-4094-a5c7-464a1b83ea10 | ||||
| CVSS 3.1 | MEDIUM | [email protected] | ||||
| CVSS 4.0 | MEDIUM | 83251b91-4cc7-4094-a5c7-464a1b83ea10 | ||||
| CVSS 4.0 | MEDIUM | [email protected] |
Solution
- Update Penpot to version 2.18.0 or newer.
- Restrict network access to the MCP server.
- Configure authentication for the WebSocket bridge.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-100868.
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-100868 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-100868
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-100868 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-100868 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
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New CVE Received by [email protected]
Sep. 27, 2026
Action Type Old Value New Value Added 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. Added CVSS V4.0 AV:A/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X Added CVSS V3.1 AV:A/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L Added CWE CWE-1327 Added Affected New affected value received. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/100xxx/CVE-2026-100868.json">CVE-2026-100868</a> Added Reference https://github.com/penpot/penpot Added Reference https://github.com/penpot/penpot/blob/1d2c37e52c733f74017d90b0fd1ae2d074a5c33d/mcp/packages/server/src/PluginBridge.ts#L52 Added Reference https://github.com/penpot/penpot/commit/b5274a44766d095247037be18c1d1918ac67ddeb Added Reference https://github.com/penpot/penpot/security/advisories/GHSA-22qr-rp27-j9wm Added Reference https://github.com/penpot/penpot/security/advisories/GHSA-ch2q-6x56-qg5r Added Reference https://www.vulncheck.com/advisories/penpot-before-2.18.0-unauthenticated-websocket-access-via-mcp-bridge