CVE-2017-12425 : What You Need to Know

A flaw in Varnish HTTP Cache versions 4.0.1 through 4.0.4, 4.1.0 through 4.1.7, 5.0.0, and 5.1.0 through 5.1.2 allows attackers to trigger an Integer Overflow, leading to a Denial-of-Service attack.

Understanding CVE-2017-12425

Varnish HTTP Cache versions 4.0.1 through 4.0.4, 4.1.0 through 4.1.7, 5.0.0, and 5.1.0 through 5.1.2 are affected by a vulnerability that can be exploited for a Denial-of-Service attack.

What is CVE-2017-12425?

A flaw in the Varnish HTTP Cache source code allows invalid client requests to trigger an assert, causing an Integer Overflow and leading to a Denial-of-Service attack by crashing the worker process.

The Impact of CVE-2017-12425

Attackers can intentionally crash the varnishd worker process, causing a Denial-of-Service attack.
Loss of cached contents due to the abrupt termination and restart of the varnishd worker process.

Technical Details of CVE-2017-12425

Vulnerability details and affected systems.

Vulnerability Description

Incorrect if statement in the varnishd source code triggers an assert on certain invalid client requests.
Results in an Integer Overflow, causing the varnishd worker process to terminate abruptly and restart.

Affected Systems and Versions

Varnish HTTP Cache versions 4.0.1 through 4.0.4, 4.1.0 through 4.1.7, 5.0.0, and 5.1.0 through 5.1.2.

Exploitation Mechanism

Attackers exploit the vulnerability by sending specific invalid requests to crash the varnishd worker process.

Mitigation and Prevention

Steps to mitigate and prevent the CVE-2017-12425 vulnerability.

Immediate Steps to Take

Update Varnish HTTP Cache to a patched version.
Monitor and restrict access to the affected systems.

Long-Term Security Practices

Regularly update and patch software to prevent known vulnerabilities.
Implement network security measures to detect and block malicious traffic.

Patching and Updates

Apply patches provided by Varnish Cache to fix the vulnerability.