{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-72916","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","state":"PUBLISHED","assignerShortName":"GitHub_M","dateReserved":"2026-08-10T17:57:26.143Z","datePublished":"2026-08-10T21:19:02.908Z","dateUpdated":"2026-08-13T15:13:23.011Z"},"containers":{"cna":{"title":"Mastodon: SSRF Protection Bypass via IPv4-compatible IPv6 Addresses","problemTypes":[{"descriptions":[{"cweId":"CWE-918","lang":"en","description":"CWE-918: Server-Side Request Forgery (SSRF)","type":"CWE"}]},{"descriptions":[{"cweId":"CWE-1286","lang":"en","description":"CWE-1286: Improper Validation of Syntactic Correctness of Input","type":"CWE"}]}],"metrics":[{"cvssV4_0":{"attackVector":"NETWORK","attackComplexity":"HIGH","attackRequirements":"PRESENT","privilegesRequired":"NONE","userInteraction":"NONE","vulnConfidentialityImpact":"NONE","vulnIntegrityImpact":"NONE","vulnAvailabilityImpact":"NONE","subConfidentialityImpact":"LOW","subIntegrityImpact":"LOW","subAvailabilityImpact":"LOW","baseScore":6.3,"baseSeverity":"MEDIUM","vectorString":"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","version":"4.0"}}],"references":[{"name":"https://github.com/mastodon/mastodon/security/advisories/GHSA-vwhj-3g83-v276","tags":["x_refsource_CONFIRM"],"url":"https://github.com/mastodon/mastodon/security/advisories/GHSA-vwhj-3g83-v276"},{"name":"https://github.com/mastodon/mastodon/commit/18c61f286f1f5718a8f517940ba384866ffa3892","tags":["x_refsource_MISC"],"url":"https://github.com/mastodon/mastodon/commit/18c61f286f1f5718a8f517940ba384866ffa3892"},{"name":"https://github.com/mastodon/mastodon/commit/467c933459c7d0e5513475b9e4888afaedfb1074","tags":["x_refsource_MISC"],"url":"https://github.com/mastodon/mastodon/commit/467c933459c7d0e5513475b9e4888afaedfb1074"},{"name":"https://github.com/mastodon/mastodon/commit/930aa9fee26bf9eaefe27826fa1061288d83373b","tags":["x_refsource_MISC"],"url":"https://github.com/mastodon/mastodon/commit/930aa9fee26bf9eaefe27826fa1061288d83373b"},{"name":"https://github.com/mastodon/mastodon/commit/da47a1bd3cd07935d7ca55a1f4f1a76f7f167e0d","tags":["x_refsource_MISC"],"url":"https://github.com/mastodon/mastodon/commit/da47a1bd3cd07935d7ca55a1f4f1a76f7f167e0d"},{"name":"https://github.com/mastodon/mastodon/releases/tag/v4.4.21","tags":["x_refsource_MISC"],"url":"https://github.com/mastodon/mastodon/releases/tag/v4.4.21"},{"name":"https://github.com/mastodon/mastodon/releases/tag/v4.5.14","tags":["x_refsource_MISC"],"url":"https://github.com/mastodon/mastodon/releases/tag/v4.5.14"},{"name":"https://github.com/mastodon/mastodon/releases/tag/v4.6.4","tags":["x_refsource_MISC"],"url":"https://github.com/mastodon/mastodon/releases/tag/v4.6.4"},{"name":"https://github.com/mastodon/mastodon/releases/tag/v4.7.0-beta.1","tags":["x_refsource_MISC"],"url":"https://github.com/mastodon/mastodon/releases/tag/v4.7.0-beta.1"}],"affected":[{"vendor":"mastodon","product":"mastodon","versions":[{"version":"< 4.4.21","status":"affected"},{"version":">= 4.5.0-beta.1, < 4.5.14","status":"affected"},{"version":">= 4.6.0-beta.1, < 4.6.4","status":"affected"}]}],"providerMetadata":{"orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","shortName":"GitHub_M","dateUpdated":"2026-08-10T21:19:02.908Z"},"descriptions":[{"lang":"en","value":"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."}],"source":{"advisory":"GHSA-vwhj-3g83-v276","discovery":"UNKNOWN"}},"adp":[{"metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-08-13T15:13:13.639949Z","id":"CVE-2026-72916","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"title":"CISA ADP Vulnrichment","providerMetadata":{"orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","shortName":"CISA-ADP","dateUpdated":"2026-08-13T15:13:23.011Z"}}]}}