Penpot before 2.18.0 Unauthenticated WebSocket Access via MCP Bridge
Summary
| CVE | CVE-2026-100868 |
|---|---|
| State | PUBLISHED |
| Assigner | VulnCheck |
| Source Priority | CVE Program / NVD first with legacy fallback |
| Published | 2026-09-27 13:16:37 UTC |
| Updated | 2026-09-27 13:16:37 UTC |
| 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. |
Risk And Classification
Primary CVSS: v4.0 5.3 MEDIUM from [email protected]
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
Problem Types: CWE-1327 | CWE-1327 Binding to an Unrestricted IP Address
| Version | Source | Type | Score | Severity | Vector |
|---|---|---|---|---|---|
| 4.0 | [email protected] | Secondary | 5.3 | MEDIUM | 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/C... |
| 4.0 | CNA | CVSS | 5.3 | MEDIUM | 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 |
| 3.1 | [email protected] | Primary | 6.3 | MEDIUM | CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L |
| 3.1 | CNA | CVSS | 6.3 | MEDIUM | CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L |
CVSS v4.0 Breakdown
Attack Vector
AdjacentAttack Complexity
LowAttack Requirements
NonePrivileges Required
NoneUser Interaction
NoneConfidentiality
LowIntegrity
LowAvailability
LowSub Conf.
NoneSub Integrity
NoneSub Availability
NoneCVSS: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
CVSS v3.1 Breakdown
Attack Vector
AdjacentAttack Complexity
LowPrivileges Required
NoneUser Interaction
NoneScope
UnchangedConfidentiality
LowIntegrity
LowAvailability
LowCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L
Vendor Declared Affected Products
| Source | Vendor | Product | Version | Platforms |
|---|---|---|---|---|
| CNA | Penpot | Penpot | affected 2.18.0 semver | Not specified |
| CNA | Penpot | @penpot/mcp | affected 2.15.4 semver | Not specified |
References
| Reference | Source | Link | Tags |
|---|---|---|---|
| www.vulncheck.com/advisories/penpot-before-2.18.0-unauthenticated-websocket-acc... | [email protected] | www.vulncheck.com | |
| github.com/penpot/penpot/security/advisories/GHSA-ch2q-6x56-qg5r | [email protected] | github.com | |
| github.com/penpot/penpot/blob/1d2c37e52c733f74017d90b0fd1ae2d074a5c33d/m... | [email protected] | github.com | |
| github.com/penpot/penpot/commit/b5274a44766d095247037be18c1d1918ac67ddeb | [email protected] | github.com | |
| github.com/penpot/penpot/security/advisories/GHSA-22qr-rp27-j9wm | [email protected] | github.com | |
| github.com/penpot/penpot | [email protected] | github.com | |
| CVE Program record | CVE.ORG | www.cve.org | canonical |
| NVD vulnerability detail | NVD | nvd.nist.gov | canonical, analysis |
Vendor Comments And Credit
Discovery Credit
CNA: George Chen (en)
There are currently no legacy QID mappings associated with this CVE.