{"id":"CVE-2026-72916","url":"https://www.cyber-defence.io/tools/cve/CVE-2026-72916","generatedAt":"2026-10-28T04:46:48.103Z","title":"An attacker could supply an address in the omitted range to bypass the ALLOWED_PRIVATE_ADDRESSES protection and make Mastodon send HTTP requests to loopback interfaces, potentially accessing private resources and services.","description":"Mastodon is a free, open-source social network server based on ActivityPub. Prior to 4.4.21, 4.5.14, 4.6.4, and 4.7.0-beta.1, PrivateAddressCheck.private_address? in app/lib/private_address_check.rb normalized IPv4-mapped IPv6 addresses but did not recognize IPv4-compatible IPv6 addresses with IPAddr#ipv4_compat?. An attacker could supply an address in the omitted range to bypass the ALLOWED_PRIVATE_ADDRESSES protection and make Mastodon send HTTP requests to loopback interfaces, potentially accessing private resources and services. Exploitation requires a system that supports the obsolete IPv4-compatible IPv6 mechanism. This issue is fixed in versions 4.4.21, 4.5.14, 4.6.4, and 4.7.0-beta.1.","published":"2026-08-10T22:17:11.000Z","lastModified":"2026-09-09T20:55:04.000Z","status":"Deferred","sourceIdentifier":"security-advisories@github.com","cvss":{"version":"4.0","score":6.3,"severity":"MEDIUM","vector":"CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:N/VA:N/SC:L/SI:L/SA:L/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/M"},"cwe":["CWE-918","CWE-1286"],"affected":[],"epss":{"score":0.00586,"percentile":0.47835,"date":"2026-10-27","history":[]},"kev":{"listed":false},"exploits":{"count":0,"verified":false,"firstPublished":null,"source":"Exploit-DB (https://gitlab.com/exploit-database/exploitdb)","entries":[]},"verdict":{"level":"low","text":"Lower severity and a low EPSS score (0.59%). Track it; it rarely justifies an emergency change on its own."},"changes":[],"references":[{"url":"https://github.com/mastodon/mastodon/commit/18c61f286f1f5718a8f517940ba384866ffa3892","source":"security-advisories@github.com"},{"url":"https://github.com/mastodon/mastodon/commit/467c933459c7d0e5513475b9e4888afaedfb1074","source":"security-advisories@github.com"},{"url":"https://github.com/mastodon/mastodon/commit/930aa9fee26bf9eaefe27826fa1061288d83373b","source":"security-advisories@github.com"},{"url":"https://github.com/mastodon/mastodon/commit/da47a1bd3cd07935d7ca55a1f4f1a76f7f167e0d","source":"security-advisories@github.com"},{"url":"https://github.com/mastodon/mastodon/releases/tag/v4.4.21","source":"security-advisories@github.com"},{"url":"https://github.com/mastodon/mastodon/releases/tag/v4.5.14","source":"security-advisories@github.com"},{"url":"https://github.com/mastodon/mastodon/releases/tag/v4.6.4","source":"security-advisories@github.com"},{"url":"https://github.com/mastodon/mastodon/releases/tag/v4.7.0-beta.1","source":"security-advisories@github.com"},{"url":"https://github.com/mastodon/mastodon/security/advisories/GHSA-vwhj-3g83-v276","source":"security-advisories@github.com"}],"sources":{"nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-72916","epss":"https://www.first.org/epss/","kev":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog","exploitdb":"https://www.exploit-db.com/"},"licence":"CC BY 4.0 — link back to the CVE Explorer if you publish the results; upstream data remains subject to its own terms."}