CVE-2021-43848 : Security Advisory and Response

h2o is an open source HTTP server that was found to have a vulnerability related to uninitialized memory access. Attackers could exploit this vulnerability to gain access to internal states of h2o server when using HTTP/3. This CVE affects versions of h2o prior to the

8c0eca3

commit.

Understanding CVE-2021-43848

This CVE involves a vulnerability that can lead to the misuse of uninitialized memory in the h2o server, potentially revealing sensitive information.

What is CVE-2021-43848?

h2o, an open source HTTP server, is susceptible to a security flaw that allows attackers to manipulate memory access and potentially access internal server states.

The Impact of CVE-2021-43848

Severity: The impact is rated as HIGH with a CVSS base score of 7.4.
Confidentiality Impact: HIGH
Availability Impact: HIGH
Attack Complexity: HIGH
Vector String: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:H

Technical Details of CVE-2021-43848

This section outlines the technical aspects of the vulnerability in h2o.

Vulnerability Description

The vulnerability in h2o allows uninitialized memory access under specific conditions, potentially leading to exposure of internal server states.

Affected Systems and Versions

Affected Product: h2o
Vendor: h2o
Affected Versions: Commits prior to 8c0eca3

Exploitation Mechanism

Attackers can exploit the vulnerability by manipulating QUIC frames to misguide the HTTP/3 server-side implementation of h2o.

Mitigation and Prevention

It is crucial to take immediate steps to mitigate the risks associated with CVE-2021-43848.

Immediate Steps to Take

Users of unreleased versions of h2o must upgrade immediately.

Long-Term Security Practices

Regularly update and patch the h2o server to prevent vulnerabilities.
Implement network security measures to detect and block malicious activities.
Perform regular security audits and vulnerability assessments.

Patching and Updates

Apply the necessary patches and updates provided by the h2o project to address the vulnerability effectively.