CVE-2023-4056 in Thunderbird
Summary
by MITRE • 08/01/2023
Memory safety bugs present in Firefox 115, Firefox ESR 115.0, Firefox ESR 102.13, Thunderbird 115.0, and Thunderbird 102.13. 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 < 116, Firefox ESR < 102.14, and Firefox ESR < 115.1.
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Analysis
by VulDB Data Team • 06/20/2025
The vulnerability identified as CVE-2023-4056 represents a critical memory safety issue affecting multiple Mozilla products including Firefox and Thunderbird across several version streams. This vulnerability stems from memory safety bugs that exist within the browser engine and email client software, specifically impacting versions prior to the mentioned security releases. The flaw manifests through memory corruption issues that could potentially be leveraged by malicious actors to execute arbitrary code on affected systems. These memory safety vulnerabilities are particularly dangerous because they often occur in the core rendering and processing components of web browsers and email clients, where untrusted input is parsed and interpreted.
The technical nature of these memory safety bugs aligns with common CWE categories including CWE-119 Improper Restriction of Operations within the Bounds of a Memory Buffer and CWE-787 Out-of-bounds Write. The vulnerabilities likely stem from insufficient bounds checking in memory allocation and deallocation operations, particularly when processing complex web content or email messages. These issues can result in buffer overflows, use-after-free conditions, or other memory corruption scenarios that allow attackers to manipulate program execution flow. The presence of evidence suggesting memory corruption indicates that these flaws can lead to unpredictable program behavior, potentially enabling attackers to inject and execute malicious code with the privileges of the affected application.
The operational impact of CVE-2023-4056 extends beyond simple browser or email client compromise, as these applications often serve as entry points for broader network attacks. When exploited successfully, these vulnerabilities could allow attackers to gain remote code execution capabilities, potentially leading to full system compromise. The attack surface is particularly concerning given that Firefox and Thunderbird are widely deployed applications with extensive user bases. The vulnerability affects not just regular Firefox releases but also the extended support releases, meaning organizations using legacy versions remain at risk. From an ATT&CK framework perspective, this vulnerability maps to techniques including T1059 Command and Scripting Interpreter and T1203 Exploitation for Client Execution, as attackers could leverage these flaws to execute malicious payloads on target systems.
Organizations should prioritize immediate patching of all affected versions to mitigate this vulnerability, with particular attention to Firefox ESR releases 102.13 and 115.0 which have extended support cycles. The recommended mitigation strategy involves updating to Firefox 116, Firefox ESR 102.14, and Firefox ESR 115.1 releases, which contain the necessary memory safety fixes. Security teams should also implement network monitoring to detect potential exploitation attempts and consider deploying additional security controls such as web application firewalls and email security solutions. The vulnerability underscores the importance of maintaining up-to-date software versions and implementing robust patch management processes, as these memory safety issues often represent the most common attack vectors for sophisticated adversaries targeting web browsers and email clients.