CVE-2025-55780: Artifex Mupdf

High severity, CVSS 7.5. EPSS: 0.4% chance of exploitation in the next 30 days.

A null pointer dereference occurs in the function break_word_for_overflow_wrap() in MuPDF 1.26.4 when rendering a malformed EPUB document. Specifically, the function calls fz_html_split_flow() to split a FLOW_WORD node, but does not check if node->next is valid before accessing node->next->overflow_wrap, resulting in a crash if the split fails or returns a partial node chain.

Affected products

• Artifex Mupdf: from 1.24.0, before 1.26.7 (fixed in 1.26.7)

Published 2025-09-23. Last modified 2026-06-17.