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This feature is well established and works across many devices and browser versions. Its been available across browsers since November 2016.
The HTTP Content-Security-Policy (CSP) sandbox directive enables a sandbox for the requested resource similar to the <iframe> sandbox attribute.
It applies restrictions to a page's actions including preventing popups, preventing the execution of plugins and scripts, and enforcing a same-origin policy.
| CSP version | 1.1 / 2 |
|---|---|
| Directive type | Document directive |
This directive is not supported in the <meta> element or by the Content-Security-policy-Report-Only header field.
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Content-Security-Policy: sandbox;
Content-Security-Policy: sandbox <value>;
where <value> can optionally be one of the following values:
allow-downloadsAllows downloading files through an <a> or <area> element with the download attribute, as well as through the navigation that leads to a download of a file.
This works regardless of whether the user clicked on the link, or JS code initiated it without user interaction.
allow-formsAllows the page to submit forms. If this keyword is not used, form will be displayed as normal, but submitting it will not trigger input validation, sending data to a web server or closing a dialog.
allow-modalsAllows the page to open modal windows by Window.alert(), Window.confirm(), Window.print() and Window.prompt(), while opening a <dialog> is allowed regardless of this keyword. It also allows the page to receive BeforeUnloadEvent event.
allow-orientation-lockLets the resource lock the screen orientation.
allow-pointer-lockAllows the page to use the Pointer Lock API.
allow-popupsAllows popups (created, for example, by or target="_blank").
If this keyword is not used, popup display will silently fail.
allow-popups-to-escape-sandboxAllows a sandboxed document to open new windows without forcing the sandboxing flags upon them. This will allow, for example, a third-party advertisement to be safely sandboxed without forcing the same restrictions upon the page the ad links to.
allow-presentationAllows embedders to have control over whether an iframe can start a presentation session.
allow-same-originAllows a sandboxed resource to retain its origin.
A sandboxed resource is otherwise treated as being from an opaque origin, which ensures that it will always fail same-origin policy checks, and hence cannot access localstorage and document.cookie and some JavaScript APIs.
The Origin of sandboxed resources without the allow-same-origin keyword is null.
allow-scriptsAllows the page to run scripts (but not create pop-up windows). If this keyword is not used, this operation is not allowed.
allow-storage-access-by-user-activation Lets the resource request access to the parent's storage capabilities with the Storage Access API.
allow-top-navigationLets the resource navigate the top-level browsing context (the one named _top).
allow-top-navigation-by-user-activationLets the resource navigate the top-level browsing context, but only if initiated by a user gesture.
allow-top-navigation-to-custom-protocolsAllows navigations to non-http protocols built into browser or registered by a website. This feature is also activated by allow-popups or allow-top-navigation keyword.
Note:
The allow-top-navigation and related values only make sense for embedded documents (such as child iframes). For standalone documents, these values have no effect, as the top-level browsing context is the document itself.
Content-Security-Policy: sandbox allow-scripts;
| Specification |
|---|
| Content Security Policy Level 3 # directive-sandbox |
Content-Security-Policysandbox attribute on <iframe>
elementsThis page was last modified on Nov 30, 2025 by MDN contributors.
Reason: CORS disabledReason: CORS header 'Access-Control-Allow-Origin' does not match 'xyz'Reason: CORS header 'Access-Control-Allow-Origin' missingReason: CORS header 'Origin' cannot be addedReason: CORS preflight channel did not succeedReason: CORS request did not succeedReason: CORS request external redirect not allowedReason: CORS request not HTTPReason: Credential is not supported if the CORS header 'Access-Control-Allow-Origin' is '*'Reason: Did not find method in CORS header 'Access-Control-Allow-Methods'Reason: expected 'true' in CORS header 'Access-Control-Allow-Credentials'Reason: invalid token 'xyz' in CORS header 'Access-Control-Allow-Headers'Reason: invalid token 'xyz' in CORS header 'Access-Control-Allow-Methods'Reason: missing token 'xyz' in CORS header 'Access-Control-Allow-Headers' from CORS preflight channelReason: Multiple CORS header 'Access-Control-Allow-Origin' not allowedAcceptAccept-CHAccept-EncodingAccept-LanguageAccept-PatchAccept-PostAccept-RangesAccess-Control-Allow-CredentialsAccess-Control-Allow-HeadersAccess-Control-Allow-MethodsAccess-Control-Allow-OriginAccess-Control-Expose-HeadersAccess-Control-Max-AgeAccess-Control-Request-HeadersAccess-Control-Request-MethodActivate-Storage-AccessAgeAllowAlt-SvcAlt-UsedAttribution-Reporting-EligibleAttribution-Reporting-Register-SourceAttribution-Reporting-Register-TriggerAuthorizationAvailable-DictionaryCache-ControlClear-Site-DataConnectionContent-DigestContent-DispositionContent-DPRContent-EncodingContent-LanguageContent-LengthContent-LocationContent-RangeContent-Security-PolicyContent-Security-Policy-Report-OnlyContent-TypeCookieCritical-CHCross-Origin-Embedder-PolicyCross-Origin-Embedder-Policy-Report-OnlyCross-Origin-Opener-PolicyCross-Origin-Resource-PolicyDateDevice-MemoryDictionary-IDDNTDownlinkDPREarly-DataECTETagExpectExpect-CTExpiresForwardedFromHostIdempotency-KeyIf-MatchIf-Modified-SinceIf-None-MatchIf-RangeIf-Unmodified-SinceIntegrity-PolicyIntegrity-Policy-Report-OnlyKeep-AliveLast-ModifiedLinkLocationMax-ForwardsNELNo-Vary-SearchObserve-Browsing-TopicsOriginOrigin-Agent-ClusterPermissions-PolicyPermissions-Policy-Report-OnlyPragmaPreferPreference-AppliedPriorityProxy-AuthenticateProxy-AuthorizationRangeRefererReferrer-PolicyRefreshReport-ToReporting-EndpointsRepr-DigestRetry-AfterRTTSave-DataSec-Browsing-TopicsSec-CH-Device-MemorySec-CH-DPRSec-CH-Prefers-Color-SchemeSec-CH-Prefers-Reduced-MotionSec-CH-Prefers-Reduced-TransparencySec-CH-UASec-CH-UA-ArchSec-CH-UA-BitnessSec-CH-UA-Form-FactorsSec-CH-UA-Full-VersionSec-CH-UA-Full-Version-ListSec-CH-UA-MobileSec-CH-UA-ModelSec-CH-UA-PlatformSec-CH-UA-Platform-VersionSec-CH-UA-WoW64Sec-CH-Viewport-HeightSec-CH-Viewport-WidthSec-CH-WidthSec-Fetch-DestSec-Fetch-ModeSec-Fetch-SiteSec-Fetch-Storage-AccessSec-Fetch-UserSec-GPCSec-Private-State-TokenSec-Private-State-Token-Crypto-VersionSec-Private-State-Token-LifetimeSec-PurposeSec-Redemption-RecordSec-Speculation-TagsSec-WebSocket-AcceptSec-WebSocket-ExtensionsSec-WebSocket-KeySec-WebSocket-ProtocolSec-WebSocket-VersionServerServer-TimingService-WorkerService-Worker-AllowedService-Worker-Navigation-PreloadSet-CookieSet-LoginSourceMapSpeculation-RulesStrict-Transport-SecuritySupports-Loading-ModeTETiming-Allow-OriginTkTrailerTransfer-EncodingUpgradeUpgrade-Insecure-RequestsUse-As-DictionaryUser-AgentVaryViaViewport-WidthWant-Content-DigestWant-Repr-DigestWarningWidthWWW-AuthenticateX-Content-Type-OptionsX-DNS-Prefetch-ControlX-Forwarded-ForX-Forwarded-HostX-Forwarded-ProtoX-Frame-OptionsX-Permitted-Cross-Domain-PoliciesX-Powered-ByX-Robots-TagX-XSS-Protection100 Continue101 Switching Protocols102 Processing103 Early Hints200 OK201 Created202 Accepted203 Non-Authoritative Information204 No Content205 Reset Content206 Partial Content207 Multi-Status208 Already Reported226 IM Used300 Multiple Choices301 Moved Permanently302 Found303 See Other304 Not Modified307 Temporary Redirect308 Permanent Redirect400 Bad Request401 Unauthorized402 Payment Required403 Forbidden404 Not Found405 Method Not Allowed406 Not Acceptable407 Proxy Authentication Required408 Request Timeout409 Conflict410 Gone411 Length Required412 Precondition Failed413 Content Too Large414 URI Too Long415 Unsupported Media Type416 Range Not Satisfiable417 Expectation Failed418 I'm a teapot421 Misdirected Request422 Unprocessable Content423 Locked424 Failed Dependency425 Too Early426 Upgrade Required428 Precondition Required429 Too Many Requests431 Request Header Fields Too Large451 Unavailable For Legal Reasons500 Internal Server Error501 Not Implemented502 Bad Gateway503 Service Unavailable504 Gateway Timeout505 HTTP Version Not Supported506 Variant Also Negotiates507 Insufficient Storage508 Loop Detected510 Not Extended511 Network Authentication 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