Which versions of MuPDF are affected by CVE-2025-71382?

MuPDF, a widely-embedded document processing library, contains a denial-of-service vulnerability affecting any application that handles EPUB files.. A patch is available.

Is there a public PoC exploit available for CVE-2025-71382?

Yes, a public proof-of-concept exploit is available for CVE-2025-71382. Prioritise patching immediately. EPSS: 0.3%.

How to fix or mitigate CVE-2025-71382?

Within 24 hours: Identify all applications and systems using MuPDF library versions prior to 1.27.0-rc1, prioritizing those processing untrusted or externally-sourced EPUB documents. Within 7 days: Apply the vendor-released patch by updating to MuPDF 1.27.0-rc1 or later across all affected instances and redeploy dependent applications. Within 30 days: Complete a full audit of patching across all infrastructure and evaluate network segmentation or input validation controls to limit EPUB processing from untrusted sources.

MuPDF CVE-2025-71382

Q: What is the CVSS score of CVE-2025-71382?

CVE-2025-71382 has a CVSS 4.0 base score of 7.1 (High). CVSS vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X. EPSS exploitation probability: 0.3%.

EUVD-2025-210322 HIGH

Uncontrolled Recursion (CWE-674)

2026-06-23 VulnCheck

GHSA-mhwh-83qc-j6x4

Denial Of Service Mupdf

7.1

CVSS 4.0 · Vendor: VulnCheck

Severity by source

Vendor (VulnCheck) PRIMARY

7.1 HIGH

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

vuln.today AI

6.5 MEDIUM

Network-delivered EPUB, low complexity, no privileges, user must open the file (UI:R), and impact is limited to a process crash so only A:H.

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

4.0 AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

Primary rating from Vendor (VulnCheck).

CVSS VectorVendor: VulnCheck

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

Scope

Lifecycle Timeline

Source Code Evidence Fetched

Jun 23, 2026 - 17:51 vuln.today

Analysis Generated

Jun 23, 2026 - 17:51 vuln.today

DescriptionCVE.org

MuPDF before 1.27.0-rc1 contains an uncontrolled recursion vulnerability in the EPUB CSS rendering engine that allows remote attackers to cause a denial of service by supplying a maliciously crafted EPUB file with deeply nested HTML elements and inline CSS styles. The function value_from_inheritable_property() in css-apply.c recurses through the CSS property inheritance chain without a depth limit, exhausting the process stack and causing a crash in any application using MuPDF for EPUB rendering.

AnalysisAI

Denial of service in MuPDF before 1.27.0-rc1 allows remote attackers to crash any application embedding the library for EPUB rendering by supplying a crafted EPUB file containing deeply nested HTML elements and inline CSS. The flaw lives in the CSS property inheritance walker (value_from_inheritable_property() in css-apply.c), which recurses without a depth bound and exhausts the process stack. Publicly available exploit code exists via the Artifex bug tracker, but the issue is not listed in CISA KEV and CVSS 4.0 base is 7.1 (availability-only impact).

Technical ContextAI

MuPDF is Artifex Software's lightweight C library and viewer for rendering PDF, XPS, and EPUB documents, embedded in many third-party readers (SumatraPDF, KOReader, zathura-mupdf, and Artifex's own mupdf and mutool binaries). The root cause is CWE-674 (Uncontrolled Recursion): when the EPUB engine resolves a CSS property that is marked 'inherit' or unset, value_from_inheritable_property() recursively calls itself walking the match->up parent chain. With deeply nested DOM/CSS structures the call depth grows linearly with nesting and overruns the thread stack. The upstream commit 70b71ab22e6de4d4c44cd301c88231f623a4e94e rewrites the function as a bounded while-loop that walks match->up iteratively, eliminating the unbounded stack frames entirely.

RemediationAI

Vendor-released patch: upgrade MuPDF to 1.27.0-rc1 or any later release that includes commit 70b71ab22e6de4d4c44cd301c88231f623a4e94e, which rewrites value_from_inheritable_property() to iterate rather than recurse; downstream maintainers that vendor MuPDF should cherry-pick that single commit. If immediate upgrade is not possible, disable EPUB ingestion in the embedding application or refuse EPUB files from untrusted sources at the gateway, accepting the trade-off that legitimate EPUB content will also be blocked. For server-side conversion pipelines, additionally run MuPDF in a sandboxed worker with a short watchdog timer and automatic restart so a single crashed worker does not interrupt the queue. Vendor advisory and commit are at https://github.com/ArtifexSoftware/mupdf/releases/tag/1.27.0-rc1 and https://github.com/ArtifexSoftware/mupdf/commit/70b71ab22e6de4d4c44cd301c88231f623a4e94e.