CVE-2026-63498: Snipe-IT: Stored XSS via Inline XML Rendering in the Uploaded Files API

Snipe-IT’s uploaded-files API accepts XML documents and later serves them inline without applying the safe-inline allowlist used by the equivalent web controller. An authenticated user who can attach files to a supported object can upload an XSLT stylesheet and an XML document that references it through xml-stylesheet. When another authorized user opens the XML file through the API with ?inline=true, the browser applies the attacker-controlled stylesheet, which produces HTML containing JavaScript in the Snipe-IT origin. This was reproduced against commit df8e3b144331d0c1cc14778f900e7646d1d9a509 (v8.6.3-231-gdf8e3b1443).

The attack requires an authenticated account with file access to at least one supported object and one victim interaction. Scope changes because attacker-controlled code executes in another user’s Snipe-IT security context. The script can read same-origin data available to the victim and perform authenticated actions as that victim.