CVE-2023-27592 (miniflux)

Miniflux is a feed reader. Since v2.0.25, Miniflux will automatically proxy images served over HTTP to prevent mixed content errors. When an outbound request made by the Go HTTP client fails, the `html.ServerError` is returned unescaped without the expected Content Security Policy header added to valid responses. By creating an RSS feed item with the inline description containing an `<img>` tag with a `srcset` attribute pointing to an invalid URL like `http:a<script>alert(1)</script>`, we can coerce the proxy handler into an …

alert client coerce content security cve errors header html http images img policy proxy reader request rss script security security policy tag url valid