{"id":"CVE-2026-33693","summary":"Lemmy's Activitypub-Federation has SSRF via 0.0.0.0 bypass in activitypub-federation-rust v4_is_invalid()","details":"Lemmy is a link aggregator and forum for the fediverse. Prior to version 0.7.0-beta.9, the `v4_is_invalid()` function in `activitypub-federation-rust` (`src/utils.rs`) does not check for `Ipv4Addr::UNSPECIFIED` (0.0.0.0). An unauthenticated attacker controlling a remote domain can point it to 0.0.0.0, bypass the SSRF protection introduced by the fix for CVE-2025-25194 (GHSA-7723-35v7-qcxw), and reach localhost services on the target server. Version 0.7.0-beta.9 patches the issue.","aliases":["GHSA-q537-8fr5-cw35"],"modified":"2026-04-10T05:43:18.044303Z","published":"2026-03-27T00:03:35.946Z","related":["GHSA-7723-35v7-qcxw","GHSA-q537-8fr5-cw35"],"database_specific":{"cna_assigner":"GitHub_M","cwe_ids":["CWE-918"],"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/33xxx/CVE-2026-33693.json"},"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/33xxx/CVE-2026-33693.json"},{"type":"FIX","url":"https://github.com/LemmyNet/activitypub-federation-rust/commit/4ae8532b17bc35755240b7f55d4a5b7665351599"},{"type":"ADVISORY","url":"https://github.com/LemmyNet/lemmy/security/advisories/GHSA-q537-8fr5-cw35"},{"type":"ADVISORY","url":"https://github.com/advisories/GHSA-7723-35v7-qcxw"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-33693"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/lemmynet/activitypub-federation-rust","events":[{"introduced":"0"},{"fixed":"5e8e9180038895ad793b7bbe9fd095fa41d48459"}],"database_specific":{"versions":[{"introduced":"0"},{"fixed":"0.7.0-beta.9"}]}}],"versions":["0.1.0","0.2.0","0.2.1","0.2.3","0.3.0","0.3.1","0.3.2","0.3.3","0.3.4","0.4.0","0.4.0-rc1","0.4.0-rc2","0.4.0-rc3","0.4.1","0.4.2","0.4.3","0.4.4","0.4.5","0.4.6","0.5.0","0.5.0-beta.1","0.5.0-beta.3","0.5.0-beta.4","0.5.0-beta.5","0.5.0-beta.6","0.5.0-beta.7","0.5.1","0.5.1-beta.1","0.5.2","0.5.3","0.5.4","0.5.5","0.5.6","0.5.7","0.5.8","0.6.0","0.6.0-alpha1","0.6.0-alpha2","0.6.0-alpha3","0.6.1","0.6.2","0.6.3","0.6.4","0.6.5","0.7.0-beta.1","0.7.0-beta.2","0.7.0-beta.3","0.7.0-beta.4","0.7.0-beta.5","0.7.0-beta.6","0.7.0-beta.7","0.7.0-beta.8"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-33693.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N"}]}