CVE-2019-6293 : Security Advisory and Response

A problem was found in the mark_beginning_as_normal function within the nfa.c file of flex version 2.6.4, leading to a stack exhaustion issue that could be exploited for a denial-of-service attack.

Understanding CVE-2019-6293

This CVE identifies a vulnerability in flex version 2.6.4 that allows remote attackers to trigger a denial-of-service attack.

What is CVE-2019-6293?

CVE-2019-6293 is a vulnerability in the mark_beginning_as_normal function in flex version 2.6.4, which can exhaust the stack due to recursive calls in specific scenarios involving multiple '*' characters.

The Impact of CVE-2019-6293

Exploiting this vulnerability could enable remote attackers to launch denial-of-service attacks on affected systems.

Technical Details of CVE-2019-6293

This section provides detailed technical information about the vulnerability.

Vulnerability Description

The issue lies in the mark_beginning_as_normal function in nfa.c in flex 2.6.4, where recursive calls to itself in certain scenarios with numerous '*' characters cause a stack exhaustion problem.

Affected Systems and Versions

Affected Version: flex 2.6.4
Affected Product: Not applicable
Affected Vendor: Not applicable

Exploitation Mechanism

Remote attackers can exploit this vulnerability by triggering the stack exhaustion issue through specific scenarios involving multiple '*' characters.

Mitigation and Prevention

To address CVE-2019-6293, follow these mitigation strategies:

Immediate Steps to Take

Update flex to a non-vulnerable version.
Implement network-level controls to filter out potentially malicious traffic.

Long-Term Security Practices

Regularly monitor and patch software for known vulnerabilities.
Conduct security assessments and penetration testing to identify and address weaknesses.

Patching and Updates

Apply patches and updates provided by the software vendor to fix the vulnerability.