CVE-2025-55780

HIGH

MuPDF 1.24.0-1.26.4 - Denial of Service via Null Pointer Dereference in break_word_for_overflow_wrap

Title source: llm
STIX 2.1

Exploitation Summary

EIP tracks 1 public exploit for CVE-2025-55780. PoCs published by ISH2YU.

AI-analyzed exploit summary This repository contains a detailed writeup for CVE-2025-55780, a null pointer dereference vulnerability in MuPDF 1.26.4's EPUB rendering function. The issue occurs in the HTML layout handling of right-to-left text with 'overflow-wrap:break-word' CSS style, leading to a crash.

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.

Exploits (1)

nomisec WRITEUP
by ISH2YU · poc
https://github.com/ISH2YU/CVE-2025-55780

This repository contains a detailed writeup for CVE-2025-55780, a null pointer dereference vulnerability in MuPDF 1.26.4's EPUB rendering function. The issue occurs in the HTML layout handling of right-to-left text with 'overflow-wrap:break-word' CSS style, leading to a crash.

Classification
Writeup 90%
Attack Type
Dos
Complexity
Moderate
Reliability
Reliable
Target: MuPDF versions 1.26.7 and before
No auth needed
Prerequisites: Affected version of MuPDF · Malicious EPUB file with specific CSS styling
devstral-2 · analyzed Feb 16, 2026 Full analysis →

References (3)

Core 3

Scores

CVSS v3 7.5
EPSS 0.0040
EPSS Percentile 31.6%
Attack Vector NETWORK
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CISA SSVC

Vulnrichment
Exploitation none
Automatable no
Technical Impact partial

Details

CWE
CWE-476
Status published
Products (1)
artifex/mupdf 1.24.0 - 1.26.7
Published Sep 23, 2025
Tracked Since Feb 18, 2026