CVE-2017-7818 in Firefox
Summary
by MITRE
A use-after-free vulnerability can occur when manipulating arrays of Accessible Rich Internet Applications (ARIA) elements within containers through the DOM. This results in a potentially exploitable crash. This vulnerability affects Firefox < 56, Firefox ESR < 52.4, and Thunderbird < 52.4.
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Analysis
by VulDB Data Team • 11/26/2025
The vulnerability identified as CVE-2017-7818 represents a critical use-after-free flaw in Mozilla's Firefox browser and Thunderbird email client that stems from improper memory management during manipulation of ARIA elements within the Document Object Model. This issue manifests when the application handles arrays of Accessible Rich Internet Applications elements that are contained within DOM structures, creating a scenario where freed memory locations may still be accessed or manipulated by subsequent operations. The vulnerability operates at the intersection of web accessibility standards and browser security mechanisms, where the ARIA specification defines roles and properties for web content to improve accessibility for users with disabilities, but the implementation fails to properly manage memory allocation and deallocation sequences.
The technical exploitation of this vulnerability occurs through specific DOM manipulation patterns involving ARIA elements that trigger memory corruption during array operations. When a web application or malicious script manipulates ARIA elements within containers, the browser's rendering engine may free memory associated with these elements while maintaining references to them, creating a use-after-free condition. This memory management flaw allows attackers to potentially execute arbitrary code by controlling the freed memory space and manipulating the execution flow of the affected applications. The vulnerability is particularly concerning because it affects core browser functionality that handles accessibility features, making it accessible through standard web browsing activities without requiring specialized attack vectors.
The operational impact of CVE-2017-7818 extends beyond simple crash conditions to potentially enable remote code execution in the context of the affected applications. This vulnerability affects Firefox versions prior to 56 and Firefox ESR versions prior to 52.4, along with Thunderbird versions before 52.4, creating a substantial attack surface across multiple Mozilla products. The exploitability of this flaw is enhanced by the fact that it can be triggered through standard web content manipulation, making it particularly dangerous in the context of web-based attacks. Security researchers have classified this vulnerability under CWE-416, which specifically addresses use-after-free conditions, and it aligns with ATT&CK techniques involving code injection and privilege escalation through memory corruption exploits.
Organizations and users affected by this vulnerability should immediately implement mitigations including updating to patched versions of Firefox, Firefox ESR, and Thunderbird, as the vendor has released security patches addressing the memory management issues in the DOM manipulation code. Additionally, administrators should consider implementing web application firewalls and content security policies to limit exposure to potentially malicious web content that could trigger this vulnerability. The mitigation strategy should also include monitoring for unusual browser behavior or crashes that might indicate exploitation attempts, particularly in environments where users frequently access untrusted web content. This vulnerability demonstrates the importance of comprehensive memory management testing in browser security and highlights the need for robust sanitization of accessibility-related code paths that interact with core DOM manipulation functions.