CVE-2025-55780

Name	CVE-2025-55780
Description	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.
Source	CVE (at NVD; CERT, LWN, oss-sec, fulldisc, Debian ELTS, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)
Debian Bugs	1116254

Vulnerable and fixed packages

The table below lists information on source packages.

Source Package	Release	Version	Status
mupdf (PTS)	bullseye	1.17.0+ds1-2	vulnerable
	bullseye (security)	1.17.0+ds1-2+deb11u1	vulnerable
	bookworm	1.21.1+ds2-1	vulnerable
	trixie	1.25.1+ds1-6	vulnerable
	forky, sid	1.25.1+ds1-7	vulnerable

The information below is based on the following data on fixed versions.

Package	Type	Release	Fixed Version	Urgency	Origin	Debian Bugs
mupdf	source	(unstable)	(unfixed)			1116254

Notes

https://bugs.ghostscript.com/show_bug.cgi?id=708720
Fixed by: https://cgit.ghostscript.com/cgi-bin/cgit.cgi/mupdf.git/commit/?id=bdd5d241748807378a78a622388e0312332513c5