What are Firefox extension IDs and why do they break CSRF?

Firefox generates a unique UUID per install for Origin headers, unlike Chrome's static ID—making simple origin checks impossible.

Does Firefox's extension UUID track users across sites?

Yes, it's persistent, unblockable, and unique per browser—worse than most cookies for fingerprinting.

How to secure extension-server comms in Firefox?

Use manual per-user tokens or proxies; no easy Origin whitelist like Chrome.

🔒 Security & Privacy

Firefox's Secret UUID Sabotage: Devs, You're Screwed

Picture this: your extension's ready to roll, server pinging Origin headers for security. Firefox? Slaps a random UUID on every install and watches you scramble.

theAIcatchup Apr 09, 2026 4 min read

Split-screen of Chrome and Firefox extension Origin headers showing mismatched IDs

⚡ Key Takeaways

Firefox uses unique per-install UUIDs in Origin headers, breaking static ID reliance 𝕏
Kills simple CSRF protection, forcing clunky token workarounds 𝕏
Creates unavoidable user tracking worse than cookies 𝕏

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theAIcatchup

Community-driven. Code-first.

#CSRF protection #Chrome extensions #Firefox extension IDs #Firefox extensions #browser extension security #browser privacy #browser security #extension IDs #privacy tracking

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Originally reported by Dev.to

⚡ Key Takeaways

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