CVE-2026-68523: Fulgur: Unbounded page slicing from attacker-controlled CSS height causes denial of service

fulgur converts untrusted HTML/CSS into PDF, commonly on a server that processes input supplied by many tenants. In versions prior to 0.19.0, a body-direct child whose CSS-resolved height greatly exceeds the page height was sliced into one fragment per page with no upper bound.

The height is taken directly from attacker-controlled HTML/CSS (height, vh units), so a few bytes such as:

<div style="height:99999999px"></div>

forced on the order of 125,000 page fragments. The pagination code then allocates vec![Vec::new(); page_count] and runs a per-page render loop, resulting in CPU and memory exhaustion. A non-finite height (one that resolves to +inf) additionally made the slicing loop’s remaining -= last_slice_h decrement never terminate, causing an infinite loop.

An attacker able to submit HTML/CSS to a fulgur-based conversion service can trigger this with a trivially small payload, denying service to the host and any co-tenants.