---
cve: "CVE-2026-42181"
severity: "MEDIUM"
cvss: 6.5
epss: "21%"
vendor: "LemmyNet"
kev: false
exploited: false
published: "2026-05-08 20:16:31"
tags: [cve, security, medium]
source: tsecurity.de CVE-Dossier
exported: "2026-09-07T07:26:13+02:00"
---

# CVE-2026-42181

> 6.5 MEDIUM · 🧪 PoC

## Beschreibung

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-Vektor

```
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
```

| Metrik | Wert | Bewertung |
|---|---|---|
| AV Angriffsvektor | Netzwerk | bad |
| AC Komplexität | Gering | bad |
| PR Privilegien | Gering | warn |
| UI Interaktion | Keine | bad |
| S Scope | Unverändert | good |
| C Vertraulichkeit | Hoch | bad |
| I Integrität | Keine | good |
| A Verfügbarkeit | Keine | good |

## Patch verfügbar (OSV)

- f32dd84d04541f8a94fee29d1f47f3f8eeaec0be (Commit)

## Referenzen

- <https://github.com/LemmyNet/lemmy/security/advisories/GHSA-h6hf-9846-xwrq>
- <https://github.com/LemmyNet/lemmy/releases/tag/0.19.18>

---
_Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/cve?cve=CVE-2026-42181) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI BITS_