CVE-2021-40391 Explained : Impact and Mitigation

This article provides details about CVE-2021-40391, an out-of-bounds write vulnerability in Gerbv, leading to code execution due to a specially-crafted drill file.

Understanding CVE-2021-40391

CVE-2021-40391 is a critical vulnerability affecting Gerbv versions 2.7.0, dev (commit b5f1eacd), and the forked version of Gerbv (commit 71493260).

What is CVE-2021-40391?

An out-of-bounds write vulnerability in the drill format T-code tool number functionality of Gerbv can be exploited by an attacker using a malicious drill file to execute arbitrary code.

The Impact of CVE-2021-40391

This vulnerability has a CVSS base score of 10, indicating a critical impact with high confidentiality, integrity, and availability impact.

Technical Details of CVE-2021-40391

CVE-2021-40391 presents the following technical information:

Vulnerability Description

Type: Out-of-bounds write
Functionality: Drill format T-code tool number
Affects: Gerbv 2.7.0, dev (commit b5f1eacd), Gerbv forked dev (commit 71493260)

Affected Systems and Versions

Affected Product: Gerbv
Affected Versions: Gerbv 2.7.0, Gerbv dev (commit b5f1eacd), Gerbv forked dev (commit 71493260)

Exploitation Mechanism

Attack Complexity: Low
Attack Vector: Network
Privileges Required: None
User Interaction: None
Scope: Changed

Mitigation and Prevention

Taking immediate steps and implementing long-term security practices are essential to mitigate the risk posed by CVE-2021-40391.

Immediate Steps to Take

Update Gerbv to a non-vulnerable version
Avoid opening untrusted drill files
Monitor network traffic for any suspicious activity

Long-Term Security Practices

Regularly update software and apply patches
Conduct security assessments and code reviews
Educate users about safe file handling practices

Patching and Updates

Check for security updates from the Gerbv vendor and apply patches promptly to address CVE-2021-40391.