CVE-2020-13111 Explained : Impact and Mitigation

NaviServer 4.99.4 to 4.99.19 allows denial of service due to the nsd/driver.c ChunkedDecode function not properly validating the length of a chunk. A remote attacker can craft a chunked-transfer request that will result in a negative value being passed to memmove via the size parameter, causing the process to crash.

Understanding CVE-2020-13111

This CVE involves a vulnerability in NaviServer versions 4.99.4 to 4.99.19 that can be exploited by a remote attacker to cause a denial of service.

What is CVE-2020-13111?

The vulnerability in NaviServer allows an attacker to crash the process by manipulating chunked-transfer requests, leading to a negative value being passed to memmove.

The Impact of CVE-2020-13111

The impact of this vulnerability is the potential for a denial of service attack, where a malicious actor can disrupt the normal operation of the NaviServer by causing it to crash.

Technical Details of CVE-2020-13111

This section provides more technical insights into the CVE.

Vulnerability Description

The vulnerability arises from the nsd/driver.c ChunkedDecode function's failure to properly validate chunk length, enabling the attacker to trigger a process crash.

Affected Systems and Versions

Systems running NaviServer versions 4.99.4 to 4.99.19 are affected by this vulnerability.

Exploitation Mechanism

A remote attacker can exploit this vulnerability by crafting a specific chunked-transfer request that results in passing a negative value to memmove via the size parameter, leading to a crash.

Mitigation and Prevention

Protecting systems from CVE-2020-13111 requires immediate actions and long-term security practices.

Immediate Steps to Take

Apply vendor-supplied patches or updates to mitigate the vulnerability.
Monitor network traffic for any suspicious chunked-transfer requests.

Long-Term Security Practices

Regularly update and patch software to address known vulnerabilities.
Implement network security measures to detect and prevent denial of service attacks.

Patching and Updates

Stay informed about security advisories and updates from NaviServer to apply patches promptly.