{
  "affected": [
    {
      "ranges": [
        {
          "database_specific": {
            "cpe": "cpe:2.3:a:joinmastodon:mastodon:*:*:*:*:*:*:*:*",
            "extracted_events": [
              {
                "introduced": "0"
              },
              {
                "fixed": "4.3.22"
              },
              {
                "introduced": "4.4.0"
              },
              {
                "fixed": "4.4.16"
              },
              {
                "introduced": "4.5.0"
              },
              {
                "fixed": "4.5.9"
              }
            ],
            "source": "CPE_RANGE"
          },
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "128393e2b4be5e7472fe4d59edd63d7b927831e5"
            },
            {
              "introduced": "69e14246b838443985a541e97327494b8d2fdffb"
            },
            {
              "fixed": "7cbce428fd9f7b34f3d879417f0722f131e9d01f"
            },
            {
              "introduced": "26c78392f88afccebb8a88b68bc9994a9ce12648"
            },
            {
              "fixed": "ff7266cf38935cea896db714d94c4ca3803d7744"
            }
          ],
          "repo": "https://github.com/mastodon/mastodon",
          "type": "GIT"
        }
      ]
    }
  ],
  "aliases": [
    "GHSA-5r37-qpwq-2jhh"
  ],
  "database_specific": {
    "cna_assigner": "GitHub_M",
    "cwe_ids": [
      "CWE-841"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/41xxx/CVE-2026-41259.json"
  },
  "details": "Mastodon is a free, open-source social network server based on ActivityPub. Prior to v4.5.9, v4.4.16, and v4.3.22, Mastodon allows restricting new user sign-up based on e-mail domain names, and performs basic validation on e-mail addresses, but fails to restrict characters that are interpreted differently by some mailing servers. This vulnerability is fixed in v4.5.9, v4.4.16, and v4.3.22.",
  "id": "CVE-2026-41259",
  "modified": "2026-07-08T05:37:03.147802783Z",
  "published": "2026-04-23T18:55:20.854Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/41xxx/CVE-2026-41259.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/mastodon/mastodon/security/advisories/GHSA-5r37-qpwq-2jhh"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-41259"
    }
  ],
  "schema_version": "1.7.5",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Mastodon: Insufficient verification of email addresses"
}