{"id":"CVE-2026-42180","revision":"8fa1224bff154b57b81c33ec4fa04615","records":[{"revision":"8fa1224bff154b57b81c33ec4fa04615","observedAt":"2026-10-27T11:12:01.124+00:00","statement":{"source":"nvd","id":"CVE-2026-42180","aliases":[],"title":"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 a…","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":"2026-05-08T20:16:31.023+00:00","modifiedAt":"2026-10-26T18:10:00.173+00:00","affected":[],"metrics":[{"system":"CVSS 3.1 · security-advisories@github.com · Secondary","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/releases/tag/0.19.18","https://github.com/LemmyNet/lemmy/security/advisories/GHSA-3jvj-v6w2-h948"],"sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-42180","license":"NIST NVD usage terms; underlying source attribution retained","enrichment":{"sourceStatus":"Deferred","weaknesses":["CWE-918"],"productCriteria":[],"sourceDates":{"published":"2026-05-08T20:16:31.023","lastModified":"2026-10-26T18:10:00.173"},"relatedAdvisories":[],"note":"NVD analysis and CPE criteria are source context, not proof that a package or your environment is affected. Complete affected data, logical configurations and SSVC are retained in the original JSON."},"key":"nvd:CVE-2026-42180","identifiers":["CVE-2026-42180"]},"retained":false,"historicalAffected":[]}],"coverage":[]}