{"id":"CVE-2026-42180","revision":"b5009dc1749742098f672b63042f2668","records":[{"revision":"b5009dc1749742098f672b63042f2668","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2026-42180","aliases":[],"title":"Lemmy: SSRF in /api/v3/post via Webmention dispatch","description":"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.","state":0,"publishedAt":"2026-05-08T19:29:04.132+00:00","modifiedAt":"2026-05-13T17:18:23.284+00:00","affected":[{"ecosystem":"Vendor product","name":"lemmy","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"vendor\": \"LemmyNet\",\n                    \"product\": \"lemmy\",\n                    \"versions\": [\n                        {\n                            \"version\": \"< 0.19.18\",\n                            \"status\": \"affected\"\n                        }\n                    ]\n                }"}],"metrics":[{"system":"CVSS 3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L","score":6.3,"severity":"MEDIUM"}],"references":["https://github.com/LemmyNet/lemmy/security/advisories/GHSA-3jvj-v6w2-h948","https://github.com/LemmyNet/lemmy/releases/tag/0.19.18"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-42180","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-42180","identifiers":["CVE-2026-42180"]},"retained":false,"historicalAffected":[]}],"coverage":[]}