CVE-2025-55029 in Firefox
Summary
by MITRE • 08/20/2025
Malicious scripts could bypass the popup blocker to spam new tabs, potentially resulting in denial of service attacks This vulnerability affects Firefox for iOS < 142.
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Analysis
by VulDB Data Team • 10/12/2025
This vulnerability represents a critical security flaw in the popup blocking mechanism of Firefox for iOS versions prior to 142, where malicious scripts can circumvent the browser's built-in protections to spawn excessive new tabs. The issue stems from insufficient validation of popup requests within the mobile browser's security architecture, allowing attackers to exploit gaps in the tab management system. The vulnerability is particularly concerning as it directly undermines the user's browsing experience and system resources by enabling unauthorized tab proliferation that can quickly exhaust device memory and processing capabilities. This represents a classic denial of service vector that can be leveraged to degrade system performance or render the device unusable through resource exhaustion.
The technical implementation of this flaw involves the manipulation of JavaScript execution contexts and browser API interactions that should normally be restricted by popup blockers. Attackers can craft malicious web pages that utilize specific timing sequences and API calls to bypass the security checks designed to prevent automatic tab opening. The vulnerability demonstrates a weakness in the browser's sandboxing mechanisms and request validation processes, where legitimate popup restrictions are circumvented through careful exploitation of browser behavior. This type of attack falls under the category of resource exhaustion attacks and can be classified as a violation of the principle of least privilege in web browser security models. The flaw is particularly dangerous in mobile environments where system resources are more constrained than on desktop platforms.
The operational impact of this vulnerability extends beyond simple annoyance to potential system compromise and user privacy risks. When malicious scripts successfully bypass popup blocking, they can flood the user's device with new tabs that may contain additional malicious content or advertising. This tab spamming behavior can lead to complete system freeze or crash, as the device struggles to manage the excessive number of concurrent browser processes. Users may experience degraded performance, battery drain, and potential exposure to additional malicious payloads through the automatically opened tabs. The vulnerability also creates opportunities for more sophisticated attacks such as clickjacking or phishing campaigns that leverage the tab proliferation to increase their effectiveness.
Mitigation strategies for this vulnerability require immediate patching of Firefox for iOS to version 142 or later, which includes enhanced popup blocking logic and improved validation of tab creation requests. Users should also implement additional browser security measures such as enabling enhanced tracking protection and regularly updating their mobile browsers to ensure they have the latest security patches. Organizations deploying Firefox for iOS should monitor for this vulnerability through their security scanning tools and ensure all devices are updated promptly. The fix addresses the underlying implementation gap by strengthening the popup blocking engine to properly validate all tab creation attempts and by implementing additional rate limiting mechanisms to prevent excessive tab spawning. This vulnerability highlights the importance of continuous security testing and validation of browser security features, particularly in mobile environments where resource constraints make denial of service attacks more impactful.
This vulnerability aligns with common weakness enumerations such as CWE-352 Cross-Site Request Forgery and CWE-400 Uncontrolled Resource Consumption, and maps to ATT&CK techniques including T1203 Exploitation for Client Execution and T1496 Resource Hijacking. The attack pattern demonstrates how seemingly minor security gaps can be amplified in mobile environments to create significant operational impacts. Security professionals should consider this vulnerability as part of broader mobile browser security assessments and ensure comprehensive testing of popup and tab management features. The incident underscores the need for robust security controls in mobile browser implementations and highlights the importance of maintaining up-to-date security practices across all mobile platforms.