CSS Exfil Protection

Name: CSS Exfil Protection
Rating: 4.76 (50 reviews)
Author: Mike Gualtieri

Guard your browser against CSS Exfil attacks! CSS Exfil is a method attackers can use to steal data from web pages using Cascading Style Sheets (CSS). This plugin sanitizes and blocks any CSS rules which may be designed to steal data.

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Features & Capabilities

CSS Exfil Protection

CSS Exfil Protection is a powerful Chrome extension designed to safeguard your browser from CSS Exfiltration attacks. CSS Exfiltration is a technique where attackers use Cascading Style Sheets (CSS) to steal sensitive data from web pages. This extension actively sanitizes and blocks any suspicious CSS rules that might be engineered to exfiltrate data, enhancing your browser's security.

By installing CSS Exfil Protection, users can browse the internet with confidence, knowing that their personal and sensitive information is shielded from stealthy CSS-based data theft attempts. The extension runs seamlessly in the background, providing robust protection without compromising browsing performance.

User Growth & Download Statistics

Add-on Privacy & Security

By:

Daily users:

Rating:

Version:

1.1.0 Last updated: 2020-08-24

Version code:

5086911

Creation date:

2018-02-06

Risk:

Permissions:

http://*/
https://*/
storage
tabs

Content scripts matches:

<all_urls>

Size:

45.73KB

URLs:

Website

Source:

Firefox Add-ons Store

Data ingested on:

2026-07-08

Compare stats and ranking:

Ranking

# 3,173 ▼ 18

Other rankings

#20 in section keyword 5 #21 in protect keyword 51 #53 in ai tech keyword 14 #77 in film keyword 9 #184 in sheets keyword 17 ▼ 3

Other platforms

CSS Exfil Protection (v1.1.0)

2,000 4.00

(3)

For Developers

Monetize with App Pass Boost with Extension Booster

Contact the developer

Chrome-Stats does not own this Firefox add-on. Please use these information below to contact the Firefox add-on developer.

Developed by:

Mike Gualtieri

Firefox Add-ons Store

https://addons.mozilla.org/firefox/addon/css-exfil-protection/

Website:

https://www.mike-gualtieri.com/css-exfil-vulnerability-tester

User Reviews

CSS Exfil Protection is valued for its added security and ease of use, helping users protect against CSS-based data leaks. However, several users report conflicts with popular extensions like uBlock Origin and problems accessing certain websites due to lack of whitelist options. While some question the legitimacy of the threat it addresses, others appreciate the developer's responsiveness to issues. Overall, it is considered useful but may require compatibility improvements to avoid disrupting web content and other extensions.

Pros

Provides additional browser protection against CSS exfiltration attacks.
Very easy to use and install.
Helps users identify if their browser is vulnerable to CSS data leaks.
Contributed by an engaged developer who follows up with users to address issues.

Cons

Conflicts with other extensions that modify or interact with CSS, such as uBlock Origin, causing CSS disruptions.
Lacks a whitelist feature, making it difficult to avoid blocking legitimate sites.
Can cause functionality issues on some websites, leading to login problems or inability to access certain services.
Some users find the extension unnecessary or think the described problem is not widely recognized or tested beyond the author's site.

Recent reviews

Really solid security extension that helps protect against a lesser-known type of attack. It blocks malicious CSS rules that could try to steal data from web pages, which adds an extra layer of safety while browsing. It works quietly in the background without affecting normal sites or slowing things down. Simple to use, reliable, and a great addition for anyone who wants stronger privacy and security online.

by Li*****, 2025-10-11

by ig*****, 2024-08-02

View all user reviews ›

Is CSS Exfil Protection Safe?

Risk impact

Risk impact measures the level of extra permissions an extension has access to. A low risk impact extension cannot do much harms, whereas a high risk impact extension can do a lot of damage like stealing your password, bypassing your security settings, and accessing your personal data. High risk impact extensions are not necessarily malicious. However, if they do turn malicious, they can be very harmful.

CSS Exfil Protection requires some sensitive permissions that could impact your browser and data security. Exercise caution before installing.

Risk impact analysis details

Critical Allows access to all websites, posing a significant security risk as it can monitor and modify data from any visited site.
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Risk likelihood

Risk likelihood measures the probability that a Firefox add-on may turn malicious. This is determined by the publisher and the Firefox add-on reputation on Firefox Add-ons Store, the amount of time the Firefox add-on has been around, and other signals about the Firefox add-on. Our algorithms are not perfect, and are subject to change as we discover new ways to detect malicious extensions. We recommend that you always exercise caution when installing a Firefox add-on.

CSS Exfil Protection is probably trust-worthy. Prefer other publishers if available. Exercise caution when installing this add-on.

Risk likelihood analysis details

High This extension website URL may be invalid
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