CVE-2026-42180

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-controll...

CVE-2026-42180 Lemmy: SSRF in /api/v3/post via Webmention dispatch

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-controll...

CVE-2026-42180 Lemmy: SSRF in /api/v3/post via Webmention dispatch

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-controll...

PT-2026-37169

Name of the Vulnerable Software and Affected Versions Lemmy versions prior to 0.19.18 Description An authenticated low-privileged user can trigger server-side HTTP requests toward internal services. This occurs when a user creates a link post in a public community via the "POST /api/v3/post"...