{
  "schema_version": "1.4.0",
  "id": "GHSA-c2c3-pqw5-5p7c",
  "modified": "2025-04-02T00:49:48Z",
  "published": "2025-04-01T22:23:49Z",
  "aliases": [
    "CVE-2025-31135"
  ],
  "summary": "Go-Guerrilla SMTP Daemon allows the PROXY command to be sent multiple times",
  "details": "### Summary\n\nThe PROXY command is accepted multiple times, allowing a client to spoof its IP address when the proxy protocol is being used.\n\n### Details\n\nWhen ProxyOn is enabled, [it looks like the PROXY command will be accepted multiple times](https://github.com/phires/go-guerrilla/blob/fca3b2d8957a746997c7e71fca39004f5c96e91f/server.go#L495), with later invocations overriding earlier ones.  The proxy protocol only supports one initial PROXY header; anything after that is considered part of the exchange between client and server, so the client is free to send further PROXY commands with whatever data it pleases.  go-guerrilla will treat these as coming from the reverse proxy, allowing a client to spoof its IP address.\n\nNote that the format of the PROXY header is [well-defined](https://www.haproxy.org/download/1.8/doc/proxy-protocol.txt).  It probably shouldn't be treated as an SMTP command; parsing it the same way is likely to result in odd behavior and could lead to other vulnerabilities.\n\n### PoC\n\nI'm working on writing a PR to fix this vulnerability.  It'll include a unit test that will serve as a PoC on the current version.\n\n### Impact\n\nAny instance with `ProxyOn` enabled (`proxyon` in the JSON config) is affected.\n\nAs far as I'm able to tell, the impact is limited to spoofing the `RemoteIP` field.  This isn't ideal, but it probably has less practical impact on an MTA than, say, a web server.",
  "severity": [
    {
      "type": "CVSS_V3",
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N"
    }
  ],
  "affected": [
    {
      "package": {
        "ecosystem": "Go",
        "name": "github.com/phires/go-guerrilla"
      },
      "ranges": [
        {
          "type": "ECOSYSTEM",
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.6.7"
            }
          ]
        }
      ]
    }
  ],
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/phires/go-guerrilla/security/advisories/GHSA-c2c3-pqw5-5p7c"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2025-31135"
    },
    {
      "type": "WEB",
      "url": "https://github.com/phires/go-guerrilla/commit/7673947f2d5204a135d7ae0b7f80759e548abee6"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/phires/go-guerrilla"
    }
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-20"
    ],
    "severity": "MODERATE",
    "github_reviewed": true,
    "github_reviewed_at": "2025-04-01T22:23:49Z",
    "nvd_published_at": "2025-04-01T22:15:21Z"
  }
}