CVE-2026-42181

The record

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 packages

Related vulnerabilities

• GHSA-h6hf-9846-xwrq Lemmy has SSRF and internal image disclosure in post link metadata via unvalidated… Same vulnerability
• CVE-2026-42180 Lemmy is a link aggregator and forum for the fediverse. Also affects lemmy_api_common
• GHSA-3jvj-v6w2-h948 Lemmy has SSRF in /api/v3/post via Webmention dispatch Also affects lemmy_api_common
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• CVE-2026-87953 Server-Side Request Forgery (SSRF) vulnerability in Drupal SAML SSO - Service Provider… CWE-918
• CVE-2026-114634 WWBN AVideo before 29.4.0 contains a blind server-side request forgery vulnerability in… CWE-918
• CVE-2026-112288 Krayin CRM 2.2.5 before 2.2.7 contains a server-side request forgery filter bypass that… CWE-918
• CVE-2026-111936 Sigma File Manager through 2.2.0 contains a server-side request forgery vulnerability… CWE-918