{"id":"CVE-2026-42181","aliases":["GHSA-h6hf-9846-xwrq"],"url":"https://o3.security/vulnerability/CVE-2026-42181","summary":"Lemmy: SSRF and internal image disclosure in post link metadata via unvalidated og:image","details":"Lemmy is a link aggregator and forum for the fediverse. Prior to version 0.19.18, Lemmy fetches metadata for user-supplied post URLs and, under the default StoreLinkPreviews image mode, downloads the preview image through local pict-rs. While the top-level page URL is checked against internal IP ranges, the extracted og:image URL is not subject to the same restriction. As a result, an authenticated low-privileged user can submit an attacker-controlled public page whose Open Graph image points to an internal image endpoint. Lemmy will fetch that internal image server-side and store a local thumbnail that can then be served back to users. This issue has been patched in version 0.19.18.","published":"2026-05-08T19:26:07.763Z","modified":"2026-08-07T11:51:05.368468995Z","cvss":{"score":6.5,"severity":"MEDIUM","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N"},"epss":{"score":0.00209,"percentile":0.11086,"asOf":"2026-08-09"},"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"crates.io","name":"lemmy_api_common","fixedVersion":"0.19.18"}],"fix":null,"references":[{"type":"WEB","url":"https://github.com/LemmyNet/lemmy/releases/tag/0.19.18"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/42xxx/CVE-2026-42181.json"},{"type":"ADVISORY","url":"https://github.com/LemmyNet/lemmy/security/advisories/GHSA-h6hf-9846-xwrq"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-42181"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-07T11:51:05.368468995Z"}}