Opener Detector

Name: Opener Detector
Author: Harry Cutts

Checks for window.opener vulnerabilities as you browse, and shows a report page whenever one is found. Can be configured to ignore individual pages or whole domains.

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Features & Capabilities

A simple browser extension which checks for window.opener vulnerabilities as you browse. When it finds one, it shows a warning page in the vulnerable tab, so that you can report or fix the vulnerability. (Use the back button to return to the page.) Individual pages and whole domains can be added to an ignore list, and by default, vulnerabilities between pages of the same origin (e.g. https://example.com/foo.html and https://example.com/bar.html) are not reported, though this can be changed in the settings.

window.opener vulnerabilities allow Web pages to control the tab which opened them. They can be fixed on many browsers simply by adding rel=noopener to your links. For more details, check out Mathias Bynens' article.

Please use responsibly. Disclose vulnerabilities you find, or fix them. Keep your hat white.

Source code is available on GitHub, under the 3-clause BSD license. Contributions welcome!

User Growth & Download Statistics

Add-on

By:

Harry Cutts

Daily users:

Version:

1.0.1resigned1 Last updated: 2024-04-25

Version code:

5728023

Creation date:

2017-05-01

Risk:

Permissions:

storage

Content scripts matches:

<all_urls>

Size:

35.56KB

URLs:

Website

Full description:

Source:

Firefox Add-ons Store

Data ingested on:

2026-06-17

Compare stats and ranking:

Ranking

# 138,259 ▲ 3,253

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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:

Harry Cutts

Firefox Add-ons Store

https://addons.mozilla.org/firefox/addon/opener-detector/

Website:

https://github.com/HarryCutts/opener-detector/issues?q=is%3Aopen%20sort%3Aupdated-desc%20

Is Opener Detector 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.

Opener Detector requires a few sensitive permissions. 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.

Opener Detector is probably trust-worthy. Prefer other publishers if available. Exercise caution when installing this add-on.

Risk likelihood analysis details

High This extension has low user count. Unpopular extensions may not be stable or safe.
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