{"schemaVersion":3,"id":"CVE-2026-23845","aliases":["GHSA-6jxm-fv7w-rw5j","GO-2026-4345"],"status":"published","duplicateOf":null,"title":null,"description":"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. 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