CVE-2021-41253 : Security Advisory and Response

Zydis library versions prior to 3.2.1 are affected by a heap buffer overflow vulnerability when using zycore string functions in formatter hooks.

Understanding CVE-2021-41253

Zydis library versions prior to 3.2.1 are susceptible to heap buffer overflow due to improper initialization of string objects within the formatter buffer, leading to heap memory corruption.

What is CVE-2021-41253?

Zydis library users in versions v3.2.0 and older can face heap buffer overflows when utilizing zycore string functions in formatter hooks.
The vulnerability arises from uninitialized fields within the formatter buffer, causing incorrect calculations and heap memory corruption.

The Impact of CVE-2021-41253

CVSS Base Score: 5.9 (Medium)
Attack Vector: Network
Availability Impact: High
Attack Complexity: High
The vulnerability does not impact Zydis' standard formatter but affects users extending the formatter using zycore string functions.

Technical Details of CVE-2021-41253

Zydis library vulnerability details and affected systems.

Vulnerability Description

Users extending Zydis' formatter using zycore string functions may encounter heap buffer overflows due to uninitialized string objects.

Affected Systems and Versions

Zydis library versions prior to 3.2.1

Exploitation Mechanism

Improper initialization of string objects within the formatter buffer

Mitigation and Prevention

Steps to mitigate and prevent the CVE-2021-41253 vulnerability.

Immediate Steps to Take

Refrain from using zycore string functions in formatter hooks
Update Zydis library to version 3.2.1 or later

Long-Term Security Practices

Regularly update library versions
Follow secure coding practices
Conduct security assessments

Patching and Updates

Patch for the vulnerability is available in Zydis version 3.2.1 and above