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

Status: published. Published: 2026-01-07. Updated: 2026-11-08.

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.

## Remediation

- fix: The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches. (source: CNA: VulnCheck) — https://github.com/microsoft/playwright/commit/1313fbd

## Affected products and versions

- Microsoft / Playwright (%40playwright/mcp): ≥ 0; < 0.0.40 (affected, semver). Source: CNA: VulnCheck

## Severity and prioritization

- CVSS 4.0: 7.2 (high); 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; source: CNA: VulnCheck

- CISA KEV: No listing in collected sources

- EPSS: 1.22% as of 2026-11-08; percentile 68.92%

- SSVC: exploitation poc; automatable no; technical impact partial; source ADP: CISA-ADP

- Weaknesses: CWE-749

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://github.com/JLLeitschuh/security-research/security/advisories/GHSA-8rgw-6xp9-2fg3 (CNA: VulnCheck; vendor-advisory)

- https://github.com/microsoft/playwright/commit/1313fbd (CNA: VulnCheck; patch)

- https://www.vulncheck.com/advisories/microsoft-playwright-mcp-server-dns-rebinding-via-missing-origin-header-validation (CNA: VulnCheck; third-party-advisory)

## Provenance

- CNA: VulnCheck: https://www.cve.org/CVERecord?id=CVE-2025-9611; retrieved 2026-11-08; source updated 2026-11-08

- FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2025-9611; retrieved 2026-11-08; source updated Not reported

Revision: 17e52a19456dc37cc8efb67ddef797b894dd8846e0a93685c34e80dd27eff676

Canonical: https://y2.dev/cve/CVE-2025-9611

## Agent and API access

Public CVE pages, Markdown, and JSON are free to read without an account or API key.

- Public catalog: https://y2.dev/cve/index.json. Follow nextCursor with the same search, filters, sort, and limit (1–100). A null cursor marks the end.

- WebMCP: search_cve_disclosures, get_cve_disclosure, get_cve_page_markdown, get_y2_cve_access. Available in compatible browsers.

- Cyber API: https://api.y2.dev/api/v2/cyber/cves and https://api.y2.dev/api/v2/cyber/cves/{cveId}.

- Y2 Pro or Elite: create a workspace API key with the intel:cyber scope and send Authorization: Bearer <Y2_API_KEY>. Setup: https://y2.dev/docs/api/create-key.

- x402: Pay per request without an account or API key. Omit Authorization, read the HTTP 402 PAYMENT-REQUIRED challenge, validate its current requirements, and retry with PAYMENT-SIGNATURE through an authorized payment client. These browser tools never make payments. Guide: https://y2.dev/docs/api/x402.

- OpenAPI: https://y2.dev/api/openapi.yaml. Agent access metadata: https://y2.dev/cve/agent.json.

Collected public records only. Check source status for coverage and freshness.