CVE-2017-5432 in Firefox
Summary
by MITRE
A use-after-free vulnerability occurs during certain text input selection resulting in a potentially exploitable crash. This vulnerability affects Thunderbird < 52.1, Firefox ESR < 45.9, Firefox ESR < 52.1, and Firefox < 53.
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Analysis
by VulDB Data Team • 11/26/2025
The vulnerability identified as CVE-2017-5432 represents a critical use-after-free condition that manifests during text input selection operations within Mozilla's browser and email client applications. This flaw stems from improper memory management practices where freed memory locations are accessed after being deallocated, creating opportunities for malicious exploitation. The vulnerability specifically targets the handling of text selection processes, making it particularly dangerous in environments where users interact with rich text content or perform complex text manipulation tasks.
The technical implementation of this vulnerability resides in the core rendering engine's text processing components, where the application fails to properly validate memory references during text selection operations. When users perform certain text selection actions, the application's memory management system deallocates specific memory blocks while simultaneously allowing code paths to reference these freed locations. This creates a race condition scenario where an attacker can potentially control the contents of the freed memory before it is accessed again, leading to arbitrary code execution possibilities. The flaw is categorized under CWE-416, which specifically addresses use-after-free vulnerabilities, and aligns with ATT&CK technique T1059.007 for command and scripting interpreter execution through browser-based attacks.
The operational impact of this vulnerability extends across multiple Mozilla products including Thunderbird email client and various Firefox browser versions, making it particularly concerning for enterprise environments where these applications are widely deployed. Organizations using affected versions face significant risk of remote code execution attacks, especially when users interact with malicious web content or email messages containing crafted text elements. The vulnerability's exploitation potential is heightened by the fact that it occurs during routine text selection operations, making it difficult for users to recognize when they might be exposed to attack vectors. Attackers can leverage this flaw to execute malicious code with the privileges of the affected application, potentially leading to complete system compromise.
Mitigation strategies for CVE-2017-5432 require immediate patching of all affected software versions, with particular emphasis on upgrading to the patched versions of Thunderbird 52.1, Firefox ESR 45.9, Firefox ESR 52.1, and Firefox 53. Organizations should implement comprehensive patch management procedures and conduct vulnerability assessments to identify any remaining instances of affected software. Additional defensive measures include implementing web application firewalls, restricting user privileges during text manipulation operations, and monitoring for suspicious memory access patterns in system logs. Network segmentation and user education regarding safe browsing practices can provide additional layers of protection while patches are deployed. Security teams should also consider implementing intrusion detection systems capable of identifying exploitation attempts targeting use-after-free vulnerabilities in browser environments.