CVE-2021-26235 : What You Need to Know

FastStone Image Viewer version 7.5 and below is impacted by a user mode write access violation vulnerability. This vulnerability occurs near NULL at 0x005bdfc9 when a user interacts with a malformed CUR file using FSViewer.exe. Attackers could exploit this flaw to conduct Denial of Service (DoS) attacks or potentially execute arbitrary code.

Understanding CVE-2021-26235

This section will delve into the details of the CVE-2021-26235 vulnerability.

What is CVE-2021-26235?

CVE-2021-26235 is a user mode write access violation vulnerability present in FastStone Image Viewer version 7.5 and below. The vulnerability is triggered when a user opens a malformed CUR file, mishandled by FSViewer.exe. This could lead to a denial of service (DoS) attack or unauthorized code execution.

The Impact of CVE-2021-26235

The impact of this vulnerability includes the potential for attackers to exploit it for DoS attacks, causing system unavailability, or for executing arbitrary code on the affected system.

Technical Details of CVE-2021-26235

In this section, we will explore the technical aspects of the CVE-2021-26235 vulnerability.

Vulnerability Description

The vulnerability involves a user mode write access violation near NULL at memory address 0x005bdfc9. It is triggered by opening or viewing a malformed CUR file using FSViewer.exe.

Affected Systems and Versions

FastStone Image Viewer versions 7.5 and below are affected by this vulnerability. Users of these versions are at risk of exploitation.

Exploitation Mechanism

Attackers can exploit this vulnerability by crafting a malicious CUR file and tricking a user into opening it with the vulnerable FastStone Image Viewer, leading to a potential DoS or code execution scenario.

Mitigation and Prevention

This section provides insights into how to mitigate and prevent the exploitation of CVE-2021-26235.

Immediate Steps to Take

Users are advised to update FastStone Image Viewer to a patched version to eliminate the vulnerability. Avoid opening suspicious or unexpected files, especially those with the .CUR extension.

Long-Term Security Practices

Implementing strong endpoint security measures, such as using reputable antivirus software and maintaining regular software updates, can help prevent similar vulnerabilities in the future.

Patching and Updates

Vendors should release security patches promptly to address CVE-2021-26235 and users must ensure they apply these updates to stay protected against potential exploits.