Langflow AI <= 1.6.9 - CORS Misconfiguration

Exploited in the wild. Listed by CISA on 2026-05-21; known to be used by ransomware.

criticalseverity

9.4CVSS score

93.2%likelihood of exploitation, next 30 days

100%of all CVEs are less likely

Readycheck to confirm it

Langflow AI versions 1.6.9 and earlier are vulnerable to a CORS misconfiguration that allows any origin to make credentialed requests. Combined with SameSite=None cookies, this enables cross-origin token theft and subsequent remote code execution via the /api/v1/validate/code endpoint.

Impact

An attacker can steal authentication tokens via CORS and execute arbitrary code on the server.

Fix

Upgrade to Langflow version 1.7.0 or later which restricts CORS origins properly.

How to confirm it

Send: GET /
Positive when: contains "Langflow"
Send: OPTIONS /api/v1/refresh
Positive when: contains in header "Access-Control-Allow-Origin: https://scanme.sh" and "Access-Control-Allow-Credentials: true" AND status 200

Run it with nuclei: nuclei -id CVE-2025-34291 -u <target>

The full check

id: CVE-2025-34291

info:
  name: Langflow AI <= 1.6.9 - CORS Misconfiguration
  author: 686f6c61
  severity: critical
  description: |
    Langflow AI versions 1.6.9 and earlier are vulnerable to a CORS misconfiguration that allows any origin to make credentialed requests. Combined with SameSite=None cookies, this enables cross-origin token theft and subsequent remote code execution via the /api/v1/validate/code endpoint.
  impact: |
    An attacker can steal authentication tokens via CORS and execute arbitrary code on the server.
  remediation: |
    Upgrade to Langflow version 1.7.0 or later which restricts CORS origins properly.
  reference:
    - https://www.obsidiansecurity.com/blog/cve-2025-34291-critical-account-takeover-and-rce-vulnerability-in-the-langflow-ai-agent-workflow-platform
    - https://nvd.nist.gov/vuln/detail/CVE-2025-34291
    - https://github.com/langflow-ai/langflow
  classification:
    cvss-metrics: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H
    cvss-score: 9.4
    cve-id: CVE-2025-34291
    epss-score: 0.93216
    epss-percentile: 0.99836
    cwe-id: CWE-942
  metadata:
    verified: true
    max-request: 2
    vendor: langflow-ai
    product: langflow
    shodan-query: html:"Langflow"
    fofa-query: body="Langflow"
  tags: cve,cve2025,langflow,cors,misconfig,vuln,oss,vkev,kev

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

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

    matchers:
      - type: word
        part: body
        words:
          - "Langflow"
        internal: true

  - raw:
      - |
        OPTIONS /api/v1/refresh HTTP/1.1
        Host: {{Hostname}}
        Origin: https://scanme.sh
        Access-Control-Request-Method: POST
        Access-Control-Request-Headers: content-type

    matchers-condition: and
    matchers:
      - type: word
        part: header
        words:
          - "Access-Control-Allow-Origin: https://scanme.sh"
          - "Access-Control-Allow-Credentials: true"
        condition: and

      - type: status
        part: header
        status:
          - 200

References

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