CVE-2021-29964 : Exploit Details and Defense Strategies

A locally-installed hostile program could send

WM_COPYDATA

messages that Firefox would process incorrectly, leading to an out-of-bounds read vulnerability affecting Thunderbird, Firefox, and Firefox ESR.

Understanding CVE-2021-29964

This CVE describes an out-of-bounds read vulnerability in Mozilla products due to incorrect processing of

WM_COPYDATA

messages, affecting Thunderbird, Firefox, and Firefox ESR.

What is CVE-2021-29964?

CVE-2021-29964 refers to a security vulnerability that could allow a locally-installed hostile program to exploit Firefox browsers on Windows by sending specially crafted messages, causing an out-of-bounds read.

The Impact of CVE-2021-29964

The vulnerability may be exploited by an attacker to read sensitive information from the affected systems, potentially leading to further compromise of user data or system integrity.

Technical Details of CVE-2021-29964

This section discusses the vulnerability description, affected systems, and the exploitation mechanism.

Vulnerability Description

A flaw in the processing of

WM_COPYDATA

messages by Firefox on Windows systems could be abused by a malicious program to trigger an out-of-bounds read.

Affected Systems and Versions

Mozilla Thunderbird versions less than 78.11, Firefox versions less than 89, and Firefox ESR versions less than 78.11 are impacted by this vulnerability.

Exploitation Mechanism

By sending specially crafted

WM_COPYDATA

messages, a locally-installed malicious program could exploit this vulnerability in Firefox, potentially leading to unauthorized information disclosure.

Mitigation and Prevention

Below are the steps towards addressing and preventing the exploitation of CVE-2021-29964.

Immediate Steps to Take

Users are advised to update their Mozilla Thunderbird, Firefox, and Firefox ESR installations to the patched versions to mitigate the out-of-bounds read vulnerability.

Long-Term Security Practices

Maintaining up-to-date software, exercising caution with software downloads, and employing security tools can enhance protection against known and potential vulnerabilities.

Patching and Updates

Regularly monitor Mozilla's security advisories and promptly apply patches and updates released by the vendor to ensure protection against known vulnerabilities.