CVE-2019-17638 : Security Advisory and Response

In Eclipse Jetty, an HTTP 431 error can be triggered due to large response headers, potentially leading to data leakage between different clients.

Understanding CVE-2019-17638

This CVE involves a vulnerability in Eclipse Jetty versions 9.4.27.v20200227 to 9.4.29.v20200521, impacting the handling of HTTP response headers.

What is CVE-2019-17638?

Jetty may release the ByteBuffer containing HTTP response headers back to the ByteBufferPool twice, allowing multiple threads to access the same ByteBuffer.
This can result in one thread writing data to the buffer while another thread fills it with different data, potentially exposing sensitive information to unintended clients.

The Impact of CVE-2019-17638

Data leakage: Client1 may see data from another request or response, including sensitive information like HTTP session IDs or authentication credentials belonging to Client2.

Technical Details of CVE-2019-17638

This section provides more in-depth technical insights into the vulnerability.

Vulnerability Description

Jetty's handling of large response headers can lead to an HTTP 431 error, causing the release of ByteBuffer back to the pool, potentially resulting in data leakage.

Affected Systems and Versions

Product: Eclipse Jetty
Vendor: The Eclipse Foundation
Versions: 9.4.27.v20200227 to 9.4.29.v20200521

Exploitation Mechanism

Threads acquiring the same ByteBuffer from the pool can lead to data inconsistency and leakage between clients.

Mitigation and Prevention

To address CVE-2019-17638, consider the following mitigation strategies:

Immediate Steps to Take

Configure a responseHeaderSize significantly larger than the requestHeaderSize to reduce the risk of data leakage.

Long-Term Security Practices

Regularly monitor and update Jetty versions to ensure the latest security patches are applied.
Implement secure coding practices to prevent similar vulnerabilities in the future.

Patching and Updates

If upgrading Jetty is not feasible, adjusting configuration settings can help mitigate the vulnerability.