CVE-2026-48788 Remark42: Cross-Site Scripting (XSS) on /api/v1/img via content-type spoofing

Remark42 is a self-hosted comment engine for blogs, articles, or any other place where readers can add comments. Versions 1.6.0 through 1.15.0 contain a Cross-Site Scripting XSS vulnerability exploitable through content-type spoofing. The Remark42 image proxy fetches an arbitrary remote URL and...

CVE-2026-48788

CVE-2026-48788 affects Remark42 (versions 1.6.0–1.15.0). The known issue is a content-type spoofing-based XSS in the image proxy: during download the proxy checks Content-Type headers to decide if a resource is an image, but the serving phase sniffing can differ, leading to a mismatch that lets H...