Microsoft Playwright MCP Server < 0.0.40 DNS Rebinding via Missing Origin Header Validation

Advisories

severity: high
date: January 6, 2026
Affecting: Playwright < 0.0.40
CVE: CVE-2025-9611
CWE: CWE-749 Exposed Dangerous Method or Function
CVSS: 7.2
CVSS V4 Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:L/VI:L/VA:H/SC:L/SI:L/SA:L
References: Researcher GitHub Advisory
Playwright GitHub Patch Commit
Credit: Jonathan Leitschuh
Description: Microsoft Playwright MCP Server versions prior to 0.0.40 fails to validate the Origin header on incoming connections. This allows an attacker to perform a DNS rebinding attack via a victim’s web browser and send unauthorized requests to a locally running MCP server, resulting in unintended invocation of MCP tool endpoints.