CVE-2023-51103 – A divide-by-zero vulnerability in Artifex MuPDF... (How to Fix)

Q: What is the severity of CVE-2023-51103?

CVE-2023-51103 has a CVSS score of 7.5 (HIGH). A divide-by-zero vulnerability in Artifex MuPDF's pixmap.c allows attackers to cause a floating point exception, potentially crashing the application. This affects users processing malicious PDF files with vulnerable versions of MuPDF. The vulnerability could lead to denial of service or potentially be leveraged for further exploitation.

📋 TL;DR

A divide-by-zero vulnerability in Artifex MuPDF's pixmap.c allows attackers to cause a floating point exception, potentially crashing the application. This affects users processing malicious PDF files with vulnerable versions of MuPDF. The vulnerability could lead to denial of service or potentially be leveraged for further exploitation.

💻 Affected Systems

Products:

Artifex MuPDF

Versions: Up to and including 1.23.4

Operating Systems: All platforms running MuPDF

Default Config Vulnerable: ⚠️ Yes

Notes: Any application or service using MuPDF library for PDF processing is affected when handling untrusted PDF files.

📦 What is this software?

Mupdf by Artifex

View all CVEs affecting Mupdf →

⚠️ Risk & Real-World Impact

🔴

Worst Case

Remote code execution through memory corruption if the floating point exception can be weaponized with additional vulnerabilities, though this is speculative.

🟠

Likely Case

Application crash (denial of service) when processing specially crafted PDF files.

🟢

If Mitigated

Minimal impact if proper input validation and sandboxing are implemented.

🌐 Internet-Facing: MEDIUM - PDF processing services exposed to untrusted uploads could be crashed, but exploitation requires specific conditions.

🏢 Internal Only: LOW - Internal users would need to process malicious PDFs, which is less likely in controlled environments.

🎯 Exploit Status

Public PoC: ⚠️ Yes

Weaponized: NO

Unauthenticated Exploit: ⚠️ Yes

Complexity: LOW

Proof of concept exists in public bug reports showing crash conditions. No evidence of weaponization for code execution.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Fixed in commit f1b5f87edd2675d5c79301e4ef2e1139f67f904b and later versions

Vendor Advisory: https://bugs.ghostscript.com/show_bug.cgi?id=707620

Restart Required: No

Instructions:

1. Update MuPDF to version after commit f1b5f87edd2675d5c79301e4ef2e1139f67f904b. 2. Recompile any applications using MuPDF library. 3. Replace existing MuPDF binaries with patched versions.

🔧 Temporary Workarounds

Input validation and sanitization

all

Implement strict PDF file validation before processing with MuPDF

Sandbox PDF processing

all

Run MuPDF in isolated containers or sandboxes with limited privileges

🧯 If You Can't Patch

Implement network segmentation to isolate PDF processing services
Deploy application allowlisting to prevent execution of vulnerable MuPDF binaries

🔍 How to Verify

Check if Vulnerable:

Check MuPDF version with 'mupdf --version' or examine library version in applications. Versions <= 1.23.4 are vulnerable.

Check Version:

mupdf --version

Verify Fix Applied:

Verify MuPDF version is after commit f1b5f87edd2675d5c79301e4ef2e1139f67f904b. Test with known malicious PDF samples from bug reports.

📡 Detection & Monitoring

Log Indicators:

Application crashes with floating point exceptions
SIGFPE signals in system logs
Unexpected termination of PDF processing services

Network Indicators:

Multiple failed PDF upload attempts followed by service disruption

SIEM Query:

source="application.logs" AND ("floating point" OR "divide by zero" OR "SIGFPE") AND process="mupdf"

📊 Metadata

CVE ID: CVE-2023-51103

CVSS v3 Score: 7.5 (HIGH)

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

CWE: CWE-369

Published: December 26, 2023

Last Updated: November 21, 2024

🔗 References

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🔗 Related Vulnerabilities

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