PhpSpreadsheet XXE Vulnerability (DC-TBD)

2024-11-19

Platform: PhpSpreadsheet

Version: All versions before 1.9.4, 2.1.3, 2.3.2, and 3.4.0

Vulnerability: XXE (XML External Entity)

Severity: High

Date: Undisclosed (potentially October 2024 based on CVE assignment trends)

What Undercode Says:

This vulnerability resides in the `XmlScanner` class of PhpSpreadsheet, a library used for reading and writing spreadsheet files. The `scan` method, designed to prevent XXE attacks, has exploitable weaknesses.

Here’s a breakdown:

1. Regex Bypass: The `scan` method uses regexes that can be bypassed using UCS-4 encoding and encoding guessing techniques. This allows attackers to inject malicious code.
2. Encoding Misdetection: The `findCharSet` method used for encoding detection is vulnerable to encodings with more than 8 bits. This is because the regex doesn’t account for null bytes, leading to the library misinterpreting the encoding.

Impact:

An attacker can exploit this vulnerability to launch XXE attacks. This could enable them to:

Steal sensitive data from the system.

Execute arbitrary code on the server.

Take control of the system.

Recommendation:

Upgrade PhpSpreadsheet to versions 1.9.4, 2.1.3, 2.3.2, or 3.4.0 (or later) to address this vulnerability.

References:

Reported By: Github.com
Undercode AI: https://ai.undercodetesting.com

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