CVE-2017-16931 Explained : Impact and Mitigation

CVE-2017-16931 was published on November 23, 2017, and affects libxml2 versions prior to 2.9.5. The vulnerability in parser.c arises from mishandling parameter-entity references, leading to incorrect function invocation when encountering a '%' character in a DTD name.

Understanding CVE-2017-16931

This CVE entry highlights a specific vulnerability in libxml2 that could potentially impact systems using affected versions.

What is CVE-2017-16931?

The issue with parser.c in libxml2 versions earlier than 2.9.5 is the mishandling of parameter-entity references, specifically when encountering a '%' character in a DTD name. This mishandling leads to an incorrect invocation of the xmlParserHandlePEReference function.

The Impact of CVE-2017-16931

The vulnerability could be exploited by a remote attacker to execute arbitrary code or cause a denial of service (DoS) condition on the affected system.

Technical Details of CVE-2017-16931

This section delves into the technical aspects of the CVE, including the vulnerability description, affected systems, and exploitation mechanism.

Vulnerability Description

The vulnerability in parser.c of libxml2 versions prior to 2.9.5 stems from the mishandling of parameter-entity references, leading to incorrect function invocation when a '%' character is encountered in a DTD name.

Affected Systems and Versions

Product: N/A
Vendor: N/A
Versions: All versions prior to 2.9.5 are affected.

Exploitation Mechanism

The vulnerability can be exploited by a remote attacker by manipulating parameter-entity references, potentially leading to arbitrary code execution or a DoS condition.

Mitigation and Prevention

In response to CVE-2017-16931, it is crucial to take immediate steps to mitigate the risk and implement long-term security practices.

Immediate Steps to Take

Update libxml2 to version 2.9.5 or later to address the vulnerability.
Monitor for any unusual activities on the system that could indicate exploitation.

Long-Term Security Practices

Regularly update software and libraries to the latest versions to patch known vulnerabilities.
Implement network security measures to prevent unauthorized access to systems.

Patching and Updates

Ensure timely patching of software and libraries, especially in response to security advisories and updates.