CVE-2025-9611: Microsoft Playwright MCP Server < 0.0.40 DNS Rebinding via Missing Origin Header Validation

Severity: high (CVSS 7.2 v4.0)
Exploited in the wild: not listed in CISA KEV
EPSS: 1.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-01-07 · updated 2026-10-08
Weakness: CWE-749

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.

Affected products

microsoft/playwright: before 0.0.40 — fixed in 0.0.40

How to fix

Upgrade to a fixed version: microsoft/playwright 0.0.40. Check the vendor advisory for mitigations.

References

https://github.com/JLLeitschuh/security-research/security/advisories/GHSA-8rgw-6xp9-2fg3
https://github.com/microsoft/playwright/commit/1313fbd
https://www.vulncheck.com/advisories/microsoft-playwright-mcp-server-dns-rebinding-via-missing-origin-header-validation

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