Hi,

The following vulnerability was published for mupdf.

CVE-2025-55780[0]:
| 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.


If you fix the vulnerability please also make sure to include the
CVE (Common Vulnerabilities & Exposures) id in your changelog entry.

For further information see:

[0] https://security-tracker.debian.org/tracker/CVE-2025-55780
https://www.cve.org/CVERecord?id=CVE-2025-55780
[1] https://bugs.ghostscript.com/show_bug.cgi?id=708720
[2] https://cgit.ghostscript.com/cgi-bin/cgit.cgi/mupdf.git/commit/?id=bdd5d241748807378a78a622388e0312332513c5

Please adjust the affected versions in the BTS as needed.

Regards,
Salvatore