CVE-2026-42181: medium-severity vulnerability in LemmyNet lemmy
Lemmy: SSRF and internal image disclosure in post link metadata via unvalidated og:image
Published · Updated
E-mail alert when it lands in KEV, gets a public PoC or its score goes up.
13Vexday Risk Score
No sign of exploitation. No public exploitation artifact known so far.
ssvc Trackcvss 6.5epss 0.3%
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.
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
Affected products
LemmyNet · lemmyRelated CVEs — LemmyNet lemmy
In the same product, most dangerous first.
CVE-2026-54739MEDIUMLemmy: Login Endpoint User Enumeration via HTTP Response Code DifferentialEPSS 0.6%CVE-2026-54738MEDIUMLemmy: Rate limit bypass via X-Forwarded-For header spoofing in actix-web ConnectionInfoEPSS 0.6%CVE-2026-54742MEDIUMLemmy: `CollectionAdd::Featured` does not check the post is in the communityEPSS 0.5%CVE-2026-54743MEDIUMLemmy: Stored XSS via markdown image alt-text in lemmy-ui html5-embedEPSS 0.5%CVE-2024-23649HIGHAny authenticated user may obtain private message details from other users on the same instanceEPSS 0.5%CVE-2026-54741MEDIUMLemmy: Blocked users can edit private messages sent before the blockEPSS 0.5%