SECURITY REPORT · EXTENSHI SCAN
Custom CSS
Firefox extension·by Kenny Ooi
79
/ 100 SAFETY SCORE
CAUTION
Mostly fine, but a few things worth reviewing before you install.
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
Custom CSS's safety score vs every other extension we've scanned
Globally
35%of extensions carry more risk
Riskier ←→ Safer
Ranked against 397,380 extensions
In Appearance
11%of appearance extensions carry more risk
Riskier ←→ Safer
Ranked against 18,877 appearance extensions
Findings
10
median 3Lower is safer
Critical findings
2
median 0Severity = Critical
Permissions
6
median 2Declared in manifest
Active users
748
median 3vs category median
Findings breakdown
Automated security signal · 10 distinct issues across 6 severities
10
distinct issues
detected
detected
Critical220%
High220%
Needs Review00%
Medium330%
Low330%
Info00%
Permissions requested
3 risky permissions of 6 total
3 high-risk permissions require attention
This extension requests 6 permissions in total. 3 of them grant broad capabilities that are worth a careful look.
High
View open tabs
Can see URLs and titles of all open tabs
High
Access all HTTP sites
Can read and modify content on all non-encrypted websites
High
Access all HTTPS sites
Can read and modify content on all encrypted websites
Medium
Store local data
Can save data locally in the browser for persistence
Info
http://*/
No additional information available.
Info
https://*/
No additional information available.
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Scan performed by extenshi.io · Aug 24, 2026
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