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SECURITY REPORT · EXTENSHI SCAN

CSS Injector

Firefox extension·by Francesco De Stefano
40
/ 100 SAFETY SCORE
DANGEROUS
Meaningful risk surface. Avoid on managed devices without review.

Likely abandonedsafety score reduced by 30 points

  • No update in over 6 years
  • Bundles libraries with known vulnerabilities and no fix in sight
Why this matters

An unmaintained extension keeps whatever flaws it shipped with, and a listing with users but no owner is an attractive target to buy and repurpose.

Automated analysis of publicly available code — not a professional security audit. It may produce false positives and does not prove an extension is unsafe or safe. Treat it as one signal among many. Disclaimer · Report an issue

How it ranks

CSS Injector's safety score vs every other extension we've scanned
Globally
14%of extensions carry more risk
This extension
Riskier ←→ Safer
Ranked against 397,240 extensions
In Appearance
3%of appearance extensions carry more risk
This extension
Riskier ←→ Safer
Ranked against 18,862 appearance extensions
Findings
51
median 3Lower is safer
Critical findings
1
median 0Severity = Critical
Permissions
8
median 2Declared in manifest
Active users
27
median 3vs category median

Findings breakdown

Automated security signal · 51 distinct issues across 6 severities
51
distinct issues
detected

Permissions requested

1 risky permission of 8 total
1 high-risk permission require attention
This extension requests 8 permissions in total. 1 of them grant broad capabilities that are worth a careful look.
High
View open tabs

Can see URLs and titles of all open tabs

Medium
Add context menu items

Can add custom items to the right-click context menu

Medium
Store local data

Can save data locally in the browser for persistence

Medium
Unlimited local storage

Can store large amounts of data locally without size limits

Medium
Access current tab

Can temporarily access the content of the active tab when you click the extension

Medium
Write to clipboard

Can place content onto your clipboard

Medium
Read clipboard

Can read text and data currently on your clipboard

Info
*://*/*

No additional information available.

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Scan performed by extenshi.io · Aug 3, 2026
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