{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-42180","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","state":"PUBLISHED","assignerShortName":"GitHub_M","dateReserved":"2026-04-25T01:53:21.582Z","datePublished":"2026-05-08T19:29:04.132Z","dateUpdated":"2026-05-13T17:18:23.284Z"},"containers":{"cna":{"title":"Lemmy: SSRF in /api/v3/post via Webmention dispatch","problemTypes":[{"descriptions":[{"cweId":"CWE-918","lang":"en","description":"CWE-918: Server-Side Request Forgery (SSRF)","type":"CWE"}]}],"metrics":[{"cvssV3_1":{"attackComplexity":"LOW","attackVector":"NETWORK","availabilityImpact":"LOW","baseScore":6.3,"baseSeverity":"MEDIUM","confidentialityImpact":"LOW","integrityImpact":"LOW","privilegesRequired":"LOW","scope":"UNCHANGED","userInteraction":"NONE","vectorString":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L","version":"3.1"}}],"references":[{"name":"https://github.com/LemmyNet/lemmy/security/advisories/GHSA-3jvj-v6w2-h948","tags":["x_refsource_CONFIRM"],"url":"https://github.com/LemmyNet/lemmy/security/advisories/GHSA-3jvj-v6w2-h948"},{"name":"https://github.com/LemmyNet/lemmy/releases/tag/0.19.18","tags":["x_refsource_MISC"],"url":"https://github.com/LemmyNet/lemmy/releases/tag/0.19.18"}],"affected":[{"vendor":"LemmyNet","product":"lemmy","versions":[{"version":"< 0.19.18","status":"affected"}]}],"providerMetadata":{"orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","shortName":"GitHub_M","dateUpdated":"2026-05-08T19:29:04.132Z"},"descriptions":[{"lang":"en","value":"Lemmy is a link aggregator and forum for the fediverse. Prior to version 0.19.18, Lemmy allows an authenticated low-privileged user to create a link post through POST /api/v3/post. When a post is created in a public community, the backend asynchronously sends a Webmention to the attacker-controlled link target. The submitted URL is checked for syntax and scheme, but the audited code path does not reject loopback, private, or link-local destinations before the Webmention request is issued. This lets a normal user trigger server-side HTTP requests toward internal services. This issue has been patched in version 0.19.18."}],"source":{"advisory":"GHSA-3jvj-v6w2-h948","discovery":"UNKNOWN"}},"adp":[{"references":[{"url":"https://github.com/LemmyNet/lemmy/security/advisories/GHSA-3jvj-v6w2-h948","tags":["exploit"]}],"metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-05-13T17:17:59.971593Z","id":"CVE-2026-42180","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":"2026-05-13T17:18:23.284Z"}}]}}