{
  "affected": [
    {
      "ranges": [
        {
          "database_specific": {
            "extracted_events": [
              {
                "introduced": "4.5.0-beta.1"
              },
              {
                "fixed": "4.5.11"
              },
              {
                "introduced": "4.3.0"
              },
              {
                "fixed": "4.4.18"
              }
            ],
            "source": "AFFECTED_FIELD"
          },
          "events": [
            {
              "introduced": "5a8ab0a3e62a8825e28bb74c1760ba6488d20c97"
            },
            {
              "fixed": "0748a5ff81b24e666ab10b8ee7fbc6f0362c8cb0"
            },
            {
              "introduced": "ab36c152f9e5f9054798504354365dcaef4e5c43"
            },
            {
              "fixed": "3555d595e2a6fcf425c73f783e8709b1e44c0872"
            }
          ],
          "repo": "https://github.com/mastodon/mastodon",
          "type": "GIT"
        }
      ]
    }
  ],
  "database_specific": {
    "cna_assigner": "GitHub_M",
    "cwe_ids": [
      "CWE-354"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/50xxx/CVE-2026-50128.json"
  },
  "details": "Mastodon is a free, open-source social network server based on ActivityPub. From 4.3.0 until 4.5.11 and 4.4.18, Mastodon has a feature to let websites credit authors of their articles. To prevent false attribution claims, Mastodon uses the attributionDomains JSON-LD term, however, an error in how it is defined makes Linked Data Signatures on the toot:attributionDomains property ineffective. An attacker can arbitrarily modify the attributionDomains value of a legitimately signed Update activity and bypass Mastodon’s signature verification. This vulnerability is fixed in 4.5.11 and 4.4.18.",
  "id": "CVE-2026-50128",
  "modified": "2026-07-15T01:49:02.209953141Z",
  "published": "2026-06-24T19:48:52.942Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/50xxx/CVE-2026-50128.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/mastodon/mastodon/security/advisories/GHSA-rwcw-vq68-g34p"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-50128"
    },
    {
      "type": "EVIDENCE",
      "url": "https://github.com/gogs/gogs/security/advisories/GHSA-pwx3-qcgw-vh7h"
    }
  ],
  "related": [
    "GHSA-pwx3-qcgw-vh7h",
    "GHSA-rwcw-vq68-g34p"
  ],
  "schema_version": "1.8.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Mastodon: Spoofing of attribution domains"
}