mailcow-dockerized Login Page has Reflected Parameter Injection / Wrong-Context XSS Escaping

{
  "id": "c5e26ba070dacb3de23b57239f29bbc6c23eb96d035e76ed601b8a2117866755",
  "url": "https://osv.dev/vulnerability/CVE-2026-40878",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "mailcow-dockerized Login Page has Reflected Parameter Injection / Wrong-Context XSS Escaping",
    "summary": "mailcow: dockerized is an open source groupware/email suite based on docker. In versions prior to 2026-03b, the mailcow web interface passes the raw `$_SERVER['REQUEST_URI']` to Twig as a global template variable and renders it inside a JavaScript string literal in the `setLang()` helper of `base.twig`, relying on Twig's default HTML auto-escaping instead of the context-appropriate `js` escaping strategy. In addition, the `query_string()` Twig helper merges all current `$_GET` parameters into the language-switching links on the login page, so attacker-supplied parameters are reflected and preserved across navigation. Version 2026-03b fixes the vulnerability.",
    "evidence": "osv:CVE-2026-40878",
    "products": [],
    "severity": "low",
    "structured": {
      "id": "CVE-2026-40878",
      "aliases": [
        "CVE-2026-40878",
        "GHSA-xv9r-j862-5hqf"
      ],
      "metrics": [
        {
          "type": "CVSS_V4",
          "score": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:A/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/mailcow/mailcow-dockerized",
              "type": "GIT",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "281cf93db359554e8f4ca941351d5ba157325cc7"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "fixed": "2026-03b"
                      }
                    ],
                    "source": "AFFECTED_FIELD",
                    "strategy": "StringRangeExpression"
                  },
                  {
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "fixed": "2026-03b"
                      }
                    ],
                    "source": "DESCRIPTION"
                  }
                ]
              }
            }
          ],
          "versions": [
            "2026-03a",
            "2026-03",
            "2026-01",
            "2025-12a",
            "2025-12",
            "2025-10a",
            "2025-10",
            "2025-09c",
            "2025-09b",
            "2025-09a",
            "2025-09",
            "2025-07",
            "2025-05",
            "2025-03b",
            "2025-03a",
            "2025-03",
            "2025-02",
            "2025-01a",
            "2025-01",
            "2024-11b",
            "2024-11a",
            "2024-11",
            "2024-08a",
            "2024-08",
            "2024-07",
            "2024-06c",
            "2024-06b",
            "2024-06a",
            "2024-06",
            "2024-04",
            "2024-02",
            "2024-01e",
            "2024-01d",
            "2024-01c",
            "2024-01b",
            "2024-01a",
            "2024-01",
            "2023-12a",
            "2023-12",
            "2023-11a",
            "2023-11",
            "2023-10a",
            "2023-10",
            "2023-09",
            "2023-08",
            "2023-07a",
            "2023-07",
            "2023-05a",
            "2023-05",
            "2023-04b",
            "2023-04a",
            "2023-04",
            "2023-03",
            "2023-02a",
            "2023-02",
            "2023-01a",
            "2023-01",
            "2022-12b",
            "2022-12a",
            "2022-12",
            "2022-11b",
            "2022-11a",
            "2022-11",
            "2022-10a",
            "2022-10",
            "2022-09a",
            "2022-09",
            "2022-08b",
            "2022-08a",
            "2022-08",
            "2022-07a",
            "2022-07",
            "2022-06b",
            "2022-06a",
            "2022-06",
            "2022-05d",
            "2022-05c",
            "2022-05b",
            "2022-05a",
            "2022-05",
            "2022-03a",
            "2022-03",
            "2022-01a",
            "2022-01"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-40878.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:32.303808092Z",
      "provider": "osv",
      "references": [
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/40xxx/CVE-2026-40878.json",
        "https://github.com/mailcow/mailcow-dockerized/security/advisories/GHSA-xv9r-j862-5hqf",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-40878"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-79"
        ],
        "cna_assigner": "GitHub_M",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/40xxx/CVE-2026-40878.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-40878",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 499551,
  "published_at": "2026-04-21T19:21:56.837+00:00"
}