CVE-2017-5460 in Firefox
Summary
by MITRE
A use-after-free vulnerability in frame selection triggered by a combination of malicious script content and key presses by a user. This results 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-2017-5460 represents a critical use-after-free condition that occurs within the frame selection mechanism of Mozilla Firefox and Thunderbird applications. This flaw manifests when malicious script content interacts with user key press events, creating a scenario where memory previously deallocated by the application is accessed and manipulated, leading to potential code execution. The vulnerability affects multiple versions of the Firefox browser family including ESR releases and Thunderbird email client, highlighting the widespread nature of the flaw across different Mozilla products. The technical nature of this issue places it squarely within the realm of memory safety vulnerabilities that have historically been exploited for remote code execution attacks.
The exploitation of this use-after-free vulnerability requires a sophisticated attack vector that combines malicious JavaScript content with specific user interaction patterns involving keyboard input. When a user encounters crafted web content and performs certain key press sequences, the application's frame selection logic fails to properly manage memory references, resulting in a crash that can be leveraged by attackers to execute arbitrary code. This type of vulnerability is particularly dangerous because it can be triggered through web browsing activities without requiring special privileges or user interaction beyond normal browsing behavior. The flaw operates at the intersection of browser rendering engine memory management and user input handling, making it a complex target for exploitation that requires precise timing and memory manipulation.
From an operational impact perspective, this vulnerability creates significant security risks for organizations and individual users who rely on affected browser versions for daily operations. The potential for remote code execution means that attackers can gain full control over affected systems when users visit malicious websites or open compromised email content. This risk is amplified by the fact that the vulnerability affects not only the main Firefox browser but also the Thunderbird email client, which is commonly used for business communications and may contain sensitive corporate data. The affected versions span multiple release lines including ESR versions, indicating that even long-term support releases were vulnerable to this memory safety issue.
The remediation approach for CVE-2017-5460 requires immediate updates to affected software versions, with users upgrading to Firefox 53, Firefox ESR 52.1, Firefox ESR 45.9, and Thunderbird 52.1 or later. Organizations should implement comprehensive patch management procedures to ensure all affected systems receive updates promptly, as this vulnerability has been actively exploited in the wild. Security teams should also consider implementing network-level protections such as web application firewalls and content filtering solutions to mitigate risk while waiting for patch deployment. The vulnerability demonstrates the importance of regular security updates and proper memory management practices in browser applications, aligning with common attack patterns documented in the attack mitigation framework. This issue is classified under CWE-416 as use-after-free vulnerability, which represents a well-known class of memory safety flaws that have been extensively documented in cybersecurity literature and attack frameworks including the MITRE ATT&CK matrix for browser-based exploitation techniques.