{"id":"CVE-2026-47389","summary":"Mastodon: SSRF protection bypass on older Ruby versions","details":"Mastodon is a free, open-source social network server based on ActivityPub. Prior to 4.5.10, 4.4.17, and 4.3.23, when using Ruby versions older than 3.4, PrivateAddressCheck.private_address? returns false for IPv4-mapped IPv6 addresses (::ffff:a.b.c.d) corresponding to some private IPv4 addresses, depending on Ruby version, this can include loopback, RFC1918 private networks, and link-local space. An attacker who controls DNS for any domain can publish an AAAA record with such a mapped address; any outbound HTTP fetch Mastodon performs against that hostname then opens a real TCP connection to the underlying IPv4 address, including 127.0.0.1 and cloud-metadata endpoints such as 169.254.169.254. This vulnerability is fixed in 4.5.10, 4.4.17, and 4.3.23.","aliases":["BIT-mastodon-2026-47389","GHSA-xx55-4rrg-8xg6"],"modified":"2026-07-15T01:49:13.667486177Z","published":"2026-06-24T19:41:21.150Z","database_specific":{"cna_assigner":"GitHub_M","cwe_ids":["CWE-184","CWE-200","CWE-918"],"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/47xxx/CVE-2026-47389.json"},"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/47xxx/CVE-2026-47389.json"},{"type":"ADVISORY","url":"https://github.com/mastodon/mastodon/security/advisories/GHSA-xx55-4rrg-8xg6"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-47389"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/mastodon/mastodon","events":[{"introduced":"5a8ab0a3e62a8825e28bb74c1760ba6488d20c97"},{"fixed":"f80b1ba92e63c3da771b405b9100f5c9abda909f"}],"database_specific":{"source":"AFFECTED_FIELD","extracted_events":[{"introduced":"4.5.0-beta.1"},{"fixed":"4.5.10"}]}}],"versions":["v4.5.9","v4.5.8","v4.5.7","v4.5.6","v4.5.5","v4.5.4","v4.5.3","v4.5.2","v4.5.1","v4.5.0","v4.5.0-rc.3","v4.5.0-rc.2","v4.5.0-rc.1","v4.5.0-beta.2","v4.5.0-beta.1"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-47389.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N"}]}