CVE-2026-100868 json
Penpot before 2.18.0 Unauthenticated WebSocket Access via MCP Bridge
published last mo. modified last mo. also EUVD-2026-87940
- cvss
- 6.3
- version 3.1, CNA
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 0.5%
- EPSS 0.5% chance of exploitation in 30 days, percentile 45%
- public exploits
- 0
- none known
Summary
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.
Patch / fix
Is CVE-2026-100868 in your stack? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.
Check with FencerCISA SSVC
- Exploitation
- Proof of concept is public
- Automatable
- no
- Technical impact
- partial
- Assessed
- last mo.
Exploit prediction
0.54% chance of exploitation in the next 30 days, higher than 45% of all scored CVEs (FIRST EPSS, 2026-11-09).
Exploits and checks
- github.com https://github.com/penpot/penpot/security/advisories/GHSA-ch2q-6x56-qg5r referenced PoC, tagged "exploit" by a source, unverified
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CNA | 4.0 | 5.3 | 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 |
| CNA | 3.1 | 6.3 | CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L |
| CNA | 4.0 | 5.3 | 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/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 |
Affected products
- penpot penpot
- penpot @penpot/mcp
Classification
- Weakness
-
- CWE-1327 Binding to an Unrestricted IP Address
References
-
github.com
/penpot/penpot/commit/b5274a44766d095247037be18c1d1918ac67ddeb
patch
-
github.com
/penpot/penpot/security/advisories/GHSA-ch2q-6x56-qg5r
vendor-advisory, exploit
-
github.com
/penpot/penpot/security/advisories/GHSA-22qr-rp27-j9wm
related, vendor-advisory
-
github.com
/penpot/penpot/blob/1d2c37e52c733f74017d90b0fd1ae2d074a5c33d/mcp/packages/server/src/PluginBridge.ts#L52
technical-description
-
github.com
/penpot/penpot
product
-
vulncheck.com
/advisories/penpot-before-2.18.0-unauthenticated-websocket-access-via-mcp-bridge
third-party-advisory
Sources
- CVE List CVE-2026-100868
- NVD CVE-2026-100868
Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.
CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.