Goodbye innerHTML, Hello setHTML: Stronger XSS Protection in Firefox 148 – Mozilla Hacks - the Web developer blog
Hacker News
February 24, 2026
AI-Generated Deep Dive Summary
Firefox 148 introduces a significant advancement in web security with the debut of the standardized Sanitizer API, marking a major step forward in combating Cross-Site Scripting (XSS) vulnerabilities. XSS remains one of the most persistent and dangerous threats on the internet, allowing attackers to inject malicious code into websites, compromising user interactions and data. The new Sanitizer API offers a straightforward solution by enabling developers to sanitize untrusted HTML before it is inserted into the DOM, thereby mitigating potential attacks.
The article highlights that Firefox's setHTML() method replaces the traditional innerHTML assignments, providing a safer default for inserting content. This integration simplifies sanitization efforts, reducing the risk of XSS attacks while requiring minimal changes to existing code. Developers can also customize the sanitization process by defining which HTML elements and attributes should be allowed or removed, offering flexibility based on specific use cases.
For instance, when using setHTML(), potentially harmful elements like script tags or event handlers are stripped out, transforming unsafe HTML into a harmless version. This approach not only enhances security but also aligns with modern web standards, making it easier for developers to adopt best practices without extensive implementation overhead. Additionally, the Sanitizer API can be paired with Trusted Types, another Mozilla initiative, to further strengthen security by centralizing control over HTML parsing and injection.
The adoption of these new features in Firefox 148 sets a precedent for other browsers to follow, potentially leading to widespread implementation across the web ecosystem. This shift toward standardized sanitization tools represents a significant leap forward in web security, offering developers an efficient way to protect their users from XSS attacks without requiring deep technical expertise or major architectural changes.
As XSS vulnerabilities continue to pose a critical threat to web applications, the introduction of the Sanitizer API and setHTML() method by Firefox 148 marks a pivotal moment in advancing a safer web experience. By integrating robust sanitization directly into HTML insertion processes, this innovation simplifies security measures for developers while raising the bar for overall web safety.
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Originally published on Hacker News on 2/24/2026