CVE-2026-42310

Affected versions of the pillow package are vulnerable to Denial of Service due to an unbounded loop when traversing PDF cross-reference trailer chains without cycle detection. The PdfParser module follows Prev pointers in PDF trailers to read cross-reference sections, but it does not track previously processed offsets, so a trailer whose Prev pointer references its own offset or forms a longer cycle causes the parser to loop indefinitely. A remote attacker who supplies a crafted PDF document can cause the parsing process to hang, consuming 100% CPU and rendering the consuming application unresponsive.