CVE-2026-23845 — Mailpit Vulnerable to Server-Side Request Forgery (SSRF) via HTML Check API
Mailpit is an email testing tool and API for developers. Versions prior to 1.28.3 are vulnerable to Server-Side Request Forgery (SSRF) via HTML Check CSS Download. The HTML Chec…
Published: 2026-01-19 · CVSS: 5.8 · CVSS 3.1
Mailpit is an email testing tool and API for developers. Versions prior to 1.28.3 are vulnerable to Server-Side Request Forgery (SSRF) via HTML Check CSS Download. The HTML Check feature (`/api/v1/message/{ID}/html-check`) is designed to analyze HTML emails for compatibility. During this process, the `inlineRemoteCSS()` function automatically downloads CSS files from external `<link rel="stylesheet" href="...">` tags to inline them for testing. Version 1.28.3 fixes the issue.
Source: CVE Program · Revision 8b16575c39f1e1810c5e863010da073d2d3285e7