mirror of
https://github.com/heygen-com/hyperframes.git
synced 2026-11-15 13:58:20 +00:00
Miguel Angel Simon Sierra
79e6680a0d
The url()/@import checks scanned raw text for the literal "url(" and
"@import". A browser decodes CSS escapes first, so fill="\75 rl(...)",
url\28...\29 and @\69mport all loaded an external resource, and
image-set("https://...") loads one with no url() at all. Reproduced in
headless Chrome: 8 of 8 payloads fired a request through the old code.
CSS can only load a resource through a function or @import, so CSS text
now passes only if it has no @import, every function is on a compute-only
allowlist (color, transform, filter and math functions), and every url()
is a same-document fragment, all checked on escape-decoded, lowercased
text. Same fix reaches media-use through the regenerated bundle.
Checked against all 13,384 files of the pinned theSVG corpus: 13,383
sanitize byte-identically; one drops an unreferenced id="XRP-(XRP)".
The parity oracle now fails on any surviving attacker host, so it no
longer shares the sanitizer's parsing blind spot.