{"id":"CVE-2026-42181","state":"PUBLISHED","title":"Lemmy: SSRF and internal image disclosure in post link metadata via unvalidated og:image","description":"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.","publishedAt":"2026-05-08T19:26:07.763Z","updatedAt":"2026-05-11T16:01:01.124Z","severity":{"score":6.5,"label":"Medium","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N","source":"GitHub_M"},"assigner":"GitHub_M","products":["LemmyNet lemmy"],"affected":[{"vendor":"LemmyNet","product":"lemmy","versions":[{"version":"< 0.19.18","status":"affected"}]}],"references":["https://github.com/LemmyNet/lemmy/security/advisories/GHSA-h6hf-9846-xwrq","https://github.com/LemmyNet/lemmy/releases/tag/0.19.18"],"weaknesses":["CWE-918"],"ingestedAt":"2026-10-29T20:11:57.932Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/42xxx/CVE-2026-42181.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-42181","state":"PUBLISHED","datePublished":"2026-05-08T19:26:07.763Z","dateUpdated":"2026-05-11T16:01:01.124Z","assignerShortName":"GitHub_M","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateReserved":"2026-04-25T01:53:21.582Z"},"containers":{"cna":{"title":"Lemmy: SSRF and internal image disclosure in post link metadata via unvalidated og:image","descriptions":[{"lang":"en","value":"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."}],"affected":[{"vendor":"LemmyNet","product":"lemmy","versions":[{"version":"< 0.19.18","status":"affected"}]}],"references":[{"url":"https://github.com/LemmyNet/lemmy/security/advisories/GHSA-h6hf-9846-xwrq","name":"https://github.com/LemmyNet/lemmy/security/advisories/GHSA-h6hf-9846-xwrq","tags":["x_refsource_CONFIRM"]},{"url":"https://github.com/LemmyNet/lemmy/releases/tag/0.19.18","name":"https://github.com/LemmyNet/lemmy/releases/tag/0.19.18","tags":["x_refsource_MISC"]}],"metrics":[{"cvssV3_1":{"attackComplexity":"LOW","attackVector":"NETWORK","availabilityImpact":"NONE","baseScore":6.5,"baseSeverity":"MEDIUM","confidentialityImpact":"HIGH","integrityImpact":"NONE","privilegesRequired":"LOW","scope":"UNCHANGED","userInteraction":"NONE","vectorString":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N","version":"3.1"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-918","lang":"en","description":"CWE-918: Server-Side Request Forgery (SSRF)","type":"CWE"}]}],"providerMetadata":{"shortName":"GitHub_M","orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateUpdated":"2026-05-08T19:26:07.763Z"},"source":{"advisory":"GHSA-h6hf-9846-xwrq","discovery":"UNKNOWN"}},"adp":[{"title":"CISA ADP Vulnrichment","references":[{"url":"https://github.com/LemmyNet/lemmy/security/advisories/GHSA-h6hf-9846-xwrq","tags":["exploit"]}],"metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-05-11T16:00:57.536211Z","id":"CVE-2026-42181","options":[{"Exploitation":"poc"},{"Automatable":"no"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-05-11T16:01:01.124Z"}}]}}}