CVE-2026-42180
Published: Fri, 08 May 2026 20:16
Summary
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 crea
Details
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.
Are YOU affected by CVE-2026-42180?
5-second check on your actual server. Reads /etc/os-release, uname -r, and dpkg-query; matches against the live USN + Debian Security Tracker feeds; tells you whether CVE-2026-42180 (and any other live CVE) applies. Anonymous, no signup.
curl https://mindsparkstack.com/scan.sh | bash
References
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