mcp-chrome-bridge (hangwin/mcp-chrome) <= 1.0.31 - CORS Origin Bypass (CSWSH)

highseverity

8.1CVSS score

0.8%likelihood of exploitation, next 30 days

57%of all CVEs are less likely

Readycheck to confirm it

mcp-chrome-bridge <=1.0.31 uses origin.startsWith for CORS, so origins like http://127.0.0.1.evil.com are wrongly allowed, letting attackers bypass CORS and access the local server.

Impact

Any website can bypass the server's CORS allowlist and make credentialed cross-origin requests to the local native-server, enabling unauthorized use of the exposed browser-automation tools (navigation, script execution, cookie/session access, screenshots) from any open browser tab.

Fix

Update to the latest version beyond 1.0.31.

How to confirm it

Send: GET /ping
Positive when: status_code == 200 and contains(tolower(body), "pong")
Send: GET /ping
Positive when: status_code == 200 and contains(tolower(header), "access-control-allow-origin: {{tolower(cors_origin)}}") and contains(tolower(header), "access-control-allow-credentials: true")

Run it with nuclei: nuclei -id CVE-2026-102878 -u <target>

The full check

id: CVE-2026-102878

info:
  name: mcp-chrome-bridge (hangwin/mcp-chrome) <= 1.0.31 - CORS Origin Bypass (CSWSH)
  author: carfeii
  severity: high
  description: |
    mcp-chrome-bridge <=1.0.31 uses origin.startsWith for CORS, so origins like http://127.0.0.1.evil.com are wrongly allowed, letting attackers bypass CORS and access the local server.
  remediation: |
    Update to the latest version beyond 1.0.31.
  impact: |
    Any website can bypass the server's CORS allowlist and make credentialed cross-origin requests to the local native-server, enabling unauthorized use of the exposed browser-automation tools (navigation, script execution, cookie/session access, screenshots) from any open browser tab.
  reference:
    - https://github.com/hangwin/mcp-chrome/issues/384
    - https://github.com/hangwin/mcp-chrome/pull/383
    - https://www.vulncheck.com/advisories/mcp-chrome-bridge-through-1.0.31-cors-origin-bypass
    - https://nvd.nist.gov/vuln/detail/CVE-2026-102878
  classification:
    cvss-metrics: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N
    cvss-score: 8.1
    cve-id: CVE-2026-102878
    epss-score: 0.00798
    epss-percentile: 0.5684
    cwe-id: CWE-346
  metadata:
    verified: true
    max-request: 2
    vendor: hangwin
    product: mcp-chrome-bridge
    shodan-query: html:"Chrome MCP"
    fofa-query: body="Chrome MCP"
  tags: cve,cve2026,mcp-chrome,cors,cswsh,misconfig

flow: http(1) && http(2)

http:
  - raw:
      - |
        GET /ping HTTP/1.1
        Host: {{Hostname}}

    matchers:
      - type: dsl
        dsl:
          - 'status_code == 200'
          - 'contains(tolower(body), "pong")'
        condition: and
        internal: true

  - raw:
      - |
        GET /ping HTTP/1.1
        Host: {{Hostname}}
        Origin: {{cors_origin}}

    payloads:
      cors_origin:
        - "http://127.0.0.1.{{rand_base(6)}}.com"

    matchers:
      - type: dsl
        dsl:
          - 'status_code == 200'
          - 'contains(tolower(header), "access-control-allow-origin: {{tolower(cors_origin)}}")'
          - 'contains(tolower(header), "access-control-allow-credentials: true")'
        condition: and

References

Use this check only on systems you are authorised to test. Where the data comes from