CVE-2025-55780

Severity: high (CVSS 7.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.4% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2025-09-23 · updated 2026-06-17
Weakness: CWE-476

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.

Affected products

Artifex MuPDF: from 1.24.0 before 1.26.7 — fixed in 1.26.7

How to fix

Upgrade to a fixed version: Artifex MuPDF 1.26.7. Check the vendor advisory for mitigations.

References

https://bugs.ghostscript.com/show_bug.cgi?id=708720
https://cgit.ghostscript.com/cgi-bin/cgit.cgi/mupdf.git/commit/?id=bdd5d241748807378a78a622388e0312332513c5
https://github.com/ISH2YU/CVE-2025-55780/tree/main

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