CVE-2021-26233 : Security Advisory and Response

FastStone Image Viewer <= 7.5 is affected by a user mode write access violation, leading to a Denial of Service (DoS) or potential code execution when processing a malformed CUR file.

Understanding CVE-2021-26233

This CVE involves a vulnerability in FastStone Image Viewer <= 7.5 that allows attackers to trigger a user mode write access violation near NULL, potentially resulting in a DoS attack or code execution.

What is CVE-2021-26233?

CVE-2021-26233 is a security vulnerability in FastStone Image Viewer <= 7.5 that enables attackers to exploit a user mode write access violation, leading to possible DoS attacks or achieving code execution by handling a malformed CUR file.

The Impact of CVE-2021-26233

The impact of CVE-2021-26233 includes the exploitation of the user mode write access violation near NULL in FastStone Image Viewer <= 7.5, which can be utilized by threat actors to carry out a Denial of Service (DoS) attack or potentially execute malicious code.

Technical Details of CVE-2021-26233

This section covers the technical aspects of the CVE.

Vulnerability Description

The vulnerability in FastStone Image Viewer <= 7.5 allows a user mode write access violation near NULL, which is triggered when a user opens or views a malformed CUR file. This mishandling by FSViewer.exe creates an opportunity for attackers to conduct a DoS attack or even execute arbitrary code.

Affected Systems and Versions

FastStone Image Viewer <= 7.5 is the affected version by this CVE. Users of this specific version are at risk of exploitation through the mishandling of CUR files.

Exploitation Mechanism

Attackers can exploit this vulnerability by crafting a specially designed CUR file and tricking a user into opening it using FastStone Image Viewer <= 7.5. The malformed file triggers the user mode write access violation near NULL, paving the way for a DoS attack or potential execution of unauthorized code.

Mitigation and Prevention

Protecting your system from CVE-2021-26233 is essential to ensure data security.

Immediate Steps to Take

Immediately updating FastStone Image Viewer to a patched version, if available, can help mitigate the risk associated with this vulnerability. Avoid opening any suspicious or unsolicited files to prevent exploitation.

Long-Term Security Practices

Enforcing a robust software update policy, practicing caution while interacting with unknown files, and maintaining up-to-date security solutions can enhance your system's overall security posture.

Patching and Updates

Stay informed about security patches released by FastStone for FastStone Image Viewer. Regularly applying updates and security patches is crucial in preventing potential exploitation of known vulnerabilities.