Individual skill
x-content-type
Use when auditing HTTP response headers on any web server or CDN for security hardening.
skills/x-content-type/SKILL.md
Source commit e8d14d049010e2ce25afcd5e8609dfcbbe63e47e
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- Matches the observed repository HEAD
- Yes
- Scanner rules are current
- Yes
- Repository scan complete
- No
- Skill scan complete
- Yes
- Observed behavior
- Network or broad shell
- Last checked
- Nov 9, 2026
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Repository context
- Repository stars (not skill ratings)
- 74,700
- Repository last updated
- Oct 31, 2026
- License
- MIT
Observed agent integration: No specific integration evidence. Standard SKILL.md installation does not imply verified compatibility.
- frontend Repository topic
- front-end-development Repository topic
- front-end-developer-tool Repository topic
- guidelines Repository topic
- checklist Repository topic
- reference Repository topic
- web-development Repository topic
- html Repository topic
- css Repository topic
- javascript Repository topic
- writing Derived category
- security Derived category
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SKILL.mdcore · 2,054 bytesreferences/rule.mddoc · 4,504 bytes
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# Set X-Content-Type-Options: nosniff
Browsers that MIME-sniff can be tricked into executing malicious JavaScript uploaded as an image — even if the server sends `Content-Type: image/png`. `nosniff` forces the browser to honor the declared type.
## Quick Reference
- Set `X-Content-Type-Options: nosniff` on all responses — the only valid value is `nosniff`
- Without this header, browsers may execute a JavaScript file disguised as an image if the server serves it with the wrong MIME type
- This header is required by OWASP's security hardening checklist and the Fetch specification
- Pair with correct `Content-Type` headers on all responses for defense in depth
- Takes 5 minutes to configure and has no compatibility issues
## Check
