CVE-2021-42756 Explained : Impact and Mitigation

Fortinet's FortiWeb versions 5.x through 6.4 are affected by multiple stack-based buffer overflow vulnerabilities, potentially allowing remote attackers to execute arbitrary code.

Understanding CVE-2021-42756

What is CVE-2021-42756?

Stack-based buffer overflow vulnerabilities in FortiWeb may permit unauthenticated remote attackers to achieve arbitrary code execution through malicious HTTP requests.

The Impact of CVE-2021-42756

The vulnerability poses a critical threat with a CVSS base score of 9.3, allowing attackers to execute unauthorized code with high impact on confidentiality, integrity, and availability.

Technical Details of CVE-2021-42756

Vulnerability Description

Multiple stack-based buffer overflow vulnerabilities exist in FortiWeb versions 5.x through 6.4.

Affected Systems and Versions

FortiWeb versions 5.x through 6.0.7, 6.1.2, 6.2.6, 6.3.16, and 6.4 are affected.

Exploitation Mechanism

Attackers can exploit the vulnerabilities by sending specially crafted HTTP requests.

Mitigation and Prevention

Immediate Steps to Take

Upgrade to FortiWeb 7.0.0 or above.
Upgrade to FortiWeb 6.3.17 or above.
Upgrade to FortiWeb 6.2.7 or above.
Upgrade to FortiWeb 6.1.3 or above.
Upgrade to FortiWeb 6.0.8 or above.

Long-Term Security Practices

Implement network segmentation to minimize the impact of potential exploits.
Regularly update and patch FortiWeb systems to address known vulnerabilities.

Patching and Updates

Apply the provided upgrades for FortiWeb versions according to the vendor's recommendations.