# CVE-2025-55780: mupdf: A null pointer dereference occurs in the function break_word_for_overflow_wrap() in MuPDF 1.26.4 when rendering a mal...

CVE-2025-55780 is fixed in mupdf on 1 platform, first by DEBIAN-CVE-2025-55780, released September 23, 2025. It is not reported as exploited. Patch Radar priority: High.

- Web page: https://patchblox.com/security/cve/CVE-2025-55780
- Priority: High
- CVSS: 7.5 (high)
- EPSS: 0.0043
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Sep 23, 2025

## 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.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | mupdf Debian 14 | 1.27.0+ds1-2 | [DEBIAN-CVE-2025-55780](https://patchblox.com/security/data/fix/linux/debian-cve-2025-55780.md) | Sep 23, 2025 |
| Linux | mupdf opensuse-leap 16.0 | 1.27.2-bp160.1.1 | [OPENSUSE-SU-2026:21180-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2026-21180-1.md) | Jun 30, 2026 |

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Data as of 2026-11-08T06:59:42Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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