CVE-2020-11080 : What You Need to Know

CVE-2020-11080 is a vulnerability in nghttp2 that allows for denial of service attacks. The issue arises from an overly large HTTP/2 SETTINGS frame payload, causing CPU spikes and service disruption.

Understanding CVE-2020-11080

What is CVE-2020-11080?

In nghttp2 versions prior to 1.41.0, a malicious client can exploit the vulnerability by repeatedly sending a specially crafted SETTINGS frame, leading to a denial of service condition.

The Impact of CVE-2020-11080

The vulnerability results in a 100% CPU spike when an attacker sends a large number of SETTINGS entries, affecting the availability of the nghttp2 service.

Technical Details of CVE-2020-11080

Vulnerability Description

The flaw in nghttp2 allows for a denial of service attack by sending an oversized HTTP/2 SETTINGS frame, overwhelming the server's CPU.

Affected Systems and Versions

Vendor: nghttp2
Product: nghttp2
Versions Affected: < 1.41.0

Exploitation Mechanism

Attackers construct a SETTINGS frame with 2400 individual settings entries, causing CPU usage to reach 100%

Mitigation and Prevention

Immediate Steps to Take

Upgrade nghttp2 to version 1.41.0 or newer to mitigate the vulnerability
Implement the nghttp2_on_frame_recv_callback to drop connections with excessive settings entries

Long-Term Security Practices

Regularly update software and apply patches promptly
Monitor and limit CPU usage to detect and prevent resource exhaustion attacks
Employ network-level protections to filter out malicious traffic

Patching and Updates

Apply the patch provided in nghttp2 version 1.41.0 to address the vulnerability