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Vulnerabilities CVE-2026-42181

CVE-2026-42181

Medium
Open
TLP:CLEAR

Lemmy: SSRF and internal image disclosure in post link metadata via unvalidated og:image

NVD CVE.org
Critical Infrastructure

AI Analysis

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Description

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.

Details

CVSS Score
6.5
EPSS Score
0.21%

11.3th percentile

CVSS Vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
Confidence
90%
Published
May 8, 2026
Last Modified
May 8, 2026
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