{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-42181", "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa", "state": "PUBLISHED", "assignerShortName": "GitHub_M", "dateReserved": "2026-04-25T01:53:21.582Z", "datePublished": "2026-05-08T19:26:07.763Z", "dateUpdated": "2026-05-11T16:01:01.124Z"}, "containers": {"cna": {"title": "Lemmy: SSRF and internal image disclosure in post link metadata via unvalidated og:image", "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": "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"}}], "references": [{"name": "https://github.com/LemmyNet/lemmy/security/advisories/GHSA-h6hf-9846-xwrq", "tags": ["x_refsource_CONFIRM"], "url": "https://github.com/LemmyNet/lemmy/security/advisories/GHSA-h6hf-9846-xwrq"}, {"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": "2026-05-08T19:26:07.763Z"}, "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."}], "source": {"advisory": "GHSA-h6hf-9846-xwrq", "discovery": "UNKNOWN"}}, "adp": [{"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"}}}], "title": "CISA ADP Vulnrichment", "providerMetadata": {"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-05-11T16:01:01.124Z"}}]}}

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{"cveTags": [], "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."}], "id": "CVE-2026-42181", "lastModified": "2026-05-12T15:31:36.920", "metrics": {"cvssMetricV31": [{"cvssData": {"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"}, "exploitabilityScore": 2.8, "impactScore": 3.6, "source": "security-advisories@github.com", "type": "Secondary"}]}, "published": "2026-05-08T20:16:31.160", "references": [{"source": "security-advisories@github.com", "url": "https://github.com/LemmyNet/lemmy/releases/tag/0.19.18"}, {"source": "security-advisories@github.com", "url": "https://github.com/LemmyNet/lemmy/security/advisories/GHSA-h6hf-9846-xwrq"}, {"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "url": "https://github.com/LemmyNet/lemmy/security/advisories/GHSA-h6hf-9846-xwrq"}], "sourceIdentifier": "security-advisories@github.com", "vulnStatus": "Deferred", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-918"}], "source": "security-advisories@github.com", "type": "Secondary"}]}

{}

{"affected": [{"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "[0,0.19.18)"}}], "enrichment": {"confidence": 100.0, "confidence_source": "matching", "scores": [{"score": 100.0, "source": "matching"}]}, "original": {"product": "lemmy", "source": "cna", "vendor": "LemmyNet"}, "product": "lemmy", "vendor": "lemmynet"}], "created": "2026-05-08T21:30:05.621193+00:00", "updated": "2026-05-08T22:30:18.071728+00:00", "vendors": ["lemmynet", "lemmynet$PRODUCT$lemmy"]}