Proton Mail
End-to-end encrypted email service with web, desktop and mobile apps, custom domain support on paid plans and a free tier.
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Security headers: B, 80 out of 100
Number 31 of 95 in the ranking. Missing 3 of the 9 headers we check.
Meets the B minimum (70/100) in our RFP clause.
With these headers missing, proton.me is more exposed to clickjacking.
Missing 3
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Permissions-Policy 0 of 10
Switches off browser features the product does not use, such as camera, microphone, location and payments, for the page and anything embedded in it.
Without it: Any script or iframe on the page, including third-party ads and chat widgets, can ask the user for camera, microphone or location access under the vendor's name.
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Cross-Origin-Opener-Policy 0 of 5
Cuts the link between the product's window and windows opened by, or opening, other sites.
Without it: A page that opens the product keeps a handle on its window and can later redirect it to a look-alike sign-in or payment page (tab-nabbing) while the user thinks they are still on the real site. It is also part of the isolation browsers need to defend against Spectre-style attacks.
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Cross-Origin-Resource-Policy 0 of 5
Tells browsers which sites may load this site's resources.
Without it: Other sites can pull the product's responses into their own pages, which makes side-channel leaks of what a signed-in user can see easier.
Sent 6
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Content-Security-Policy 25 of 25
default-src 'self'; media-src https://static.zdassets.com https://res.cloudinary.com https://pmecdn.protonweb.com; connect-src 'self' wss: https://protonmail.zendesk.com https://ekr.zdassets.com blob: https://account.proton.me https://reports.proton.me https://telemetry.proton.me https://*.algolia.net https://*.algolianet.com https://go.getproton.me https://noembed.com https://boards-api.greenhouse.io https://proton.me https://*.paypal.com https://*.paypalobjects.com https://growth.proton.me ; script-src 'self' blob: 'unsafe-eval' 'unsafe-inline' https://static.zdassets.com https://pmecdn.protonweb.com https://www.youtube.com https://platform.twitter.com https://*.paypal.com https://*.paypalobjects.com; style-src 'self' 'unsafe-inline' https://pmecdn.protonweb.com https://*.paypal.com https://*.paypalobjects.com; font-src 'self' https://pmecdn.protonweb.com; img-src 'self' data: blob: https:; frame-src 'self' data: blob: https://www.youtube-nocookie.com https://platform.twitter.com https://*.paypal.com https://*.paypalobjects.com; object-src 'self' data: blob:; child-src 'self' data: blob: https://*.paypal.com https://*.paypalobjects.com; report-uri https://reports.proton.me/reports/csp; frame-ancestors 'self' https://*.proton.me;
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Strict-Transport-Security 20 of 20
max-age=31536000; includeSubDomains; preload
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X-Content-Type-Options 10 of 10
nosniff
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Frame protection 10 of 10
CSP frame-ancestors
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Referrer-Policy 10 of 10
strict-origin-when-cross-origin
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No version disclosure 5 of 5