CVE-2017-5404 in Firefox
Summary
by MITRE
A use-after-free error can occur when manipulating ranges in selections with one node inside a native anonymous tree and one node outside of it. This results in a potentially exploitable crash. This vulnerability affects Firefox < 52, Firefox ESR < 45.8, Thunderbird < 52, and Thunderbird < 45.8.
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Analysis
by VulDB Data Team • 11/26/2025
The vulnerability identified as CVE-2017-5404 represents a critical use-after-free flaw within the Mozilla Firefox and Thunderbird browser applications that stems from improper handling of range manipulation operations within document selection contexts. This issue specifically manifests when the selection system attempts to process ranges that span across different tree structures, particularly involving native anonymous trees which are internal DOM structures used for layout and rendering purposes. The vulnerability resides in the browser's document object model manipulation capabilities, where the selection API fails to properly validate the relationship between nodes when constructing ranges that cross boundaries between regular DOM elements and native anonymous tree elements.
The technical exploitation of this vulnerability occurs through a carefully crafted sequence of DOM operations that triggers a race condition in memory management. When the browser's selection system processes a range containing one node inside a native anonymous tree and another node outside of it, the underlying memory management routines fail to properly track the lifecycle of objects referenced within these ranges. This creates a scenario where a freed memory location may be accessed or reused before the selection system properly invalidates references to it, leading to a potential use-after-free condition that can be exploited by malicious actors to execute arbitrary code on the target system. The vulnerability is classified under CWE-416 as a use-after-free error, which represents a well-known class of memory safety issues that frequently lead to remote code execution exploits in web browsers.
The operational impact of this vulnerability extends beyond simple browser crashes to potentially enable full system compromise through remote code execution attacks. Attackers can leverage this flaw by crafting malicious web pages that trigger the specific selection conditions required to activate the use-after-free condition, potentially allowing them to execute arbitrary code with the privileges of the browser process. The affected versions include Firefox versions prior to 52 and Firefox ESR versions prior to 45.8, along with corresponding Thunderbird versions, making a significant portion of deployed browser software vulnerable to exploitation. This vulnerability aligns with ATT&CK technique T1059.007 for command and scripting interpreter and T1203 for Exploitation for Client Execution, as it enables attackers to deliver and execute malicious payloads through web-based attack vectors.
Mitigation strategies for CVE-2017-5404 primarily focus on immediate software updates and patches provided by Mozilla to address the underlying memory management issues in the selection system. Organizations should prioritize upgrading to patched versions of Firefox, Firefox ESR, and Thunderbird to eliminate the risk of exploitation. Additionally, implementing browser hardening techniques such as address space layout randomization, stack canaries, and sandboxing mechanisms can provide additional defense-in-depth layers. Network-based mitigations including web application firewalls and content filtering solutions can help detect and block exploitation attempts targeting this specific vulnerability. Security teams should also monitor for indicators of compromise related to exploitation attempts and maintain comprehensive incident response procedures for potential exploitation events. The vulnerability demonstrates the critical importance of proper memory management in complex web browser environments and underscores the need for continuous security testing and code review processes to identify similar issues before they can be exploited by malicious actors.