CSP: base-uri
The HTTP Content-Security-Policy
base-uri
directive restricts the URLs which can be used in a document's <base>
element. If this value is absent, then any URI is allowed. If this directive is absent, the user agent will use the value in the <base>
element.
CSP version | 2 |
---|---|
Directive type | Document directive |
default-src fallback |
No. Not setting this allows any URL. |
Syntax
One or more sources can be allowed for the base-uri policy:
http
Content-Security-Policy: base-uri <source>;
Content-Security-Policy: base-uri <source> <source>;
Sources
This directive uses most of the same source values for arguments as other CSP directives: CSP Source Values.
Note however that some of the values don't make sense for base-uri
, such as the keywords 'unsafe-inline'
and 'strict-dynamic'
.
Examples
Meta tag configuration
html
<meta http-equiv="Content-Security-Policy" content="base-uri 'self'" />
Apache configuration
<IfModule mod_headers.c> Header set Content-Security-Policy "base-uri 'self'"; </IfModule>
Nginx configuration
add_header Content-Security-Policy "base-uri 'self';"
Violation case
Since your domain isn't example.com
, a <base>
element with its href
set to https://example.com
will result in a CSP violation.
html
<meta http-equiv="Content-Security-Policy" content="base-uri 'self'" />
<base href="https://example.com/" />
<!--
// Error: Refused to set the document's base URI to 'https://example.com/'
// because it violates the following Content Security Policy
// directive: "base-uri 'self'"
-->
Specifications
Specification |
---|
Content Security Policy Level 3 # directive-base-uri |
Browser compatibility
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