# CVE-2025-55780: Null dereference in n/a

> A null pointer dereference in MuPDF allows attackers to cause a denial of service via a malformed EPUB document.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 23 Sep 2025
- **Updated:** 25 Sep 2025
- **Also known as:** DEBIAN-CVE-2025-55780, GHSA-756h-grq9-2jvh, UBUNTU-CVE-2025-55780

## What is CVE-2025-55780?

CVE-2025-55780 is a high-severity vulnerability in Artifex Mupdf, published on 23 Sep 2025. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official 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.

Weakness: CWE-476 (NULL Pointer Dereference)

## Which versions are affected by CVE-2025-55780?

It affects 1 product.


Products: Artifex Mupdf.

## How do I fix CVE-2025-55780?

Apply the vendor's patch.

## Is CVE-2025-55780 being exploited?

There is no known exploitation of CVE-2025-55780 in the wild and no public exploit code.

Public exploit code:

- Null Pointer Dereference in MuPDF , First CVE discovered by me  (github_poc): https://github.com/ISH2YU/CVE-2025-55780

## Other vulnerabilities in Artifex Mupdf

- [CVE-2019-7321](https://insights.sbomify.com/CVE-2019-7321/): Memory corruption in n/a (critical 9.8)
- [CVE-2016-6525](https://insights.sbomify.com/CVE-2016-6525/): Memory corruption in n/a (critical 9.8)
- [CVE-2011-0341](https://insights.sbomify.com/CVE-2011-0341/): Memory corruption in n/a (critical 9.3)
- [CVE-2016-8728](https://insights.sbomify.com/CVE-2016-8728/): Memory corruption in MuPDF (high 8.6)
- [CVE-2021-3407](https://insights.sbomify.com/CVE-2021-3407/): Use after free in mupdf (high 7.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2025-55780 and fix it if it is affected.

What it is: CVE-2025-55780 is a high-severity vulnerability in Artifex Mupdf, published on 23 Sep 2025. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2025-55780 in the wild and no public exploit code.

Affected product: Artifex Mupdf. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2025-55780/ (Markdown: https://insights.sbomify.com/CVE-2025-55780/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-55780
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-55780
- OSV: https://osv.dev/vulnerability/CVE-2025-55780

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-55780/
Summaries are generated and may contain mistakes; the official description above is the record.