CVE-2021-23978 in Firefox
Summary
by MITRE • 02/26/2021
Mozilla developers reported memory safety bugs present in Firefox 85 and Firefox ESR 78.7. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability affects Firefox < 86, Thunderbird < 78.8, and Firefox ESR < 78.8.
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Analysis
by VulDB Data Team • 03/05/2021
Mozilla Firefox and Thunderbird versions prior to 86 and 78.8 respectively contain multiple memory safety vulnerabilities that represent significant security risks to users of these applications. These memory safety bugs were identified by Mozilla developers during routine security assessments and represent a class of vulnerabilities that can potentially lead to arbitrary code execution. The affected versions include Firefox 85 and Firefox ESR 78.7, with the broader impact extending to Thunderbird versions below 78.8 and Firefox ESR versions below 78.8. The presence of memory corruption evidence in these bugs indicates that attackers could potentially exploit these flaws to manipulate memory structures and execute malicious code within the context of the affected applications.
The technical nature of these vulnerabilities falls under memory safety issues that typically involve improper handling of memory allocation, deallocation, or access patterns within the browser's rendering engine and JavaScript interpreter. These types of flaws often manifest through buffer overflows, use-after-free conditions, or double-free errors that can be exploited by attackers who craft malicious web content designed to trigger these specific memory handling failures. The memory corruption aspects suggest that attackers could potentially overwrite critical memory locations with malicious payloads, leading to complete system compromise when the vulnerable applications execute these crafted inputs.
The operational impact of these vulnerabilities extends beyond simple browser exploitation to potentially affect users across multiple platforms including Windows, macOS, and Linux systems that utilize affected versions of Firefox or Thunderbird. Attackers could leverage these memory safety issues through various attack vectors such as malicious websites, email attachments, or compromised web content that would trigger the vulnerable code paths within the applications. The potential for arbitrary code execution means that successful exploitation could allow attackers to install malware, steal sensitive data, or establish persistent access to compromised systems. These vulnerabilities represent a serious threat to user security and privacy given that browsers and email clients are frequently targeted by threat actors due to their privileged access to user data and system resources.
Organizations and individual users should prioritize immediate patching of affected systems to mitigate these security risks. Mozilla has released updates addressing these memory safety issues in Firefox 86 and Thunderbird 78.8, with Firefox ESR 78.8 also receiving the necessary security patches. System administrators should implement comprehensive patch management procedures to ensure all affected applications are updated promptly, particularly in enterprise environments where multiple users may be exposed to these vulnerabilities. The mitigation strategy should include regular monitoring of security advisories and maintaining updated security configurations to reduce the attack surface. Additional protective measures such as web application firewalls, content filtering solutions, and user education about safe browsing practices can provide additional defense layers against exploitation attempts targeting these specific memory safety vulnerabilities. These vulnerabilities align with common attack patterns documented in the attack technique framework, particularly those involving memory corruption exploitation techniques that have been consistently used in advanced persistent threat campaigns targeting web browsers and email clients.