CVE-2025-55780: mupdf Null Dereference (CVSS 7.5)

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.

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CVSS v3.1 Score

7.5

HIGH

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Weakness Type (CWE)

CWE-476 CWE-476

Affected Products

Vendor	Product	Versions
artifex	mupdf	1.24.0 — 1.26.7

References

Other 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

Frequently Asked Questions

What is CVE-2025-55780? +

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. It has a CVSS v3.1 base score of 7.5 (HIGH).

How severe is CVE-2025-55780? +

CVE-2025-55780 has a CVSS v3.1 score of 7.5 out of 10, rated HIGH. This is a high-severity vulnerability that should be prioritized for patching.

What products are affected by CVE-2025-55780? +

CVE-2025-55780 affects products from artifex, specifically: mupdf. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2025-55780? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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