text/htmlThis registration is for community review and will be submitted to the IESG for review, approval, and registration with IANA.
charsetThe charset parameter may be provided to specify the
document's character encoding, overriding any character encoding declarations in the document other than a Byte Order Mark (BOM). The parameter's value
must be one of the labels of the character encoding used to serialise the file. [ENCODING]
Entire novels have been written about the security considerations that apply to HTML documents. Many are listed in this document, to which the reader is referred for more details. Some general concerns bear mentioning here, however:
HTML is scripted language, and has a large number of APIs (some of which are described in this document). Script can expose the user to potential risks of information leakage, credential leakage, cross-site scripting attacks, cross-site request forgeries, and a host of other problems. While the designs in this specification are intended to be safe if implemented correctly, a full implementation is a massive undertaking and, as with any software, user agents are likely to have security bugs.
Even without scripting, there are specific features in HTML which, for historical reasons,
are required for broad compatibility with legacy content but that expose the user to unfortunate
security problems. In particular, the img element can be used in conjunction with
some other features as a way to effect a port scan from the user's location on the Internet.
This can expose local network topologies that the attacker would otherwise not be able to
determine.
HTML relies on a compartmentalization scheme sometimes known as the same-origin policy. An origin in most cases consists of all the pages served from the same host, on the same port, using the same protocol.
It is critical, therefore, to ensure that any untrusted content that forms part of a site be hosted on a different origin than any sensitive content on that site. Untrusted content can easily spoof any other page on the same origin, read data from that origin, cause scripts in that origin to execute, submit forms to and from that origin even if they are protected from cross-site request forgery attacks by unique tokens, and make use of any third-party resources exposed to or rights granted to that origin.
html" and "htm"
are commonly, but certainly not exclusively, used as the
extension for HTML documents.TEXTFragment identifiers used with text/html resources either refer to the
indicated part of the document or provide state information for in-page scripts.
multipart/x-mixed-replaceThis registration is for community review and will be submitted to the IESG for review, approval, and registration with IANA.
boundary (defined in RFC2046) [RFC2046]
multipart/x-mixed-replace
resource can be of any type, including types with non-trivial
security implications such as text/html.
multipart/mixed. [RFC2046]
multipart/x-mixed-replace resource.Fragment identifiers used with multipart/x-mixed-replace resources apply to each
body part as defined by the type used by that body part.
application/xhtml+xmlThis registration is for community review and will be submitted to the IESG for review, approval, and registration with IANA.
application/xml [RFC7303]application/xml [RFC7303]application/xml [RFC7303]application/xml [RFC7303]application/xml [RFC7303]application/xhtml+xml
type asserts that the resource is an XML document that likely has
a root element from the HTML namespace. Thus, the
relevant specifications are the XML specification, the Namespaces
in XML specification, and this specification. [XML] [XMLNS]
application/xml [RFC7303]application/xml [RFC7303]xhtml" and "xht"
are sometimes used as extensions for XML resources that have a
root element from the HTML namespace.TEXTFragment identifiers used with application/xhtml+xml resources have the same
semantics as with any XML MIME type. [RFC7303]
application/x-www-form-urlencodedThis registration is for community review and will be submitted to the IESG for review, approval, and registration with IANA.
In isolation, an application/x-www-form-urlencoded
payload poses no security risks. However, as this type is usually
used as part of a form submission, all the risks that apply to
HTML forms need to be considered in the context of this type.
application/x-www-form-urlencoded payloads are
defined in this specification.
application/x-www-form-urlencoded payloads.Fragment identifiers have no meaning with the application/x-www-form-urlencoded
type.
text/cache-manifestThis registration is for community review and will be submitted to the IESG for review, approval, and registration with IANA.
charsetThe charset parameter may be provided. The parameter's value must be
"utf-8". This parameter serves no purpose; it is only allowed for
compatibility with legacy servers.
Cache manifests themselves pose no immediate risk unless sensitive information is included within the manifest. Implementations, however, are required to follow specific rules when populating a cache based on a cache manifest, to ensure that certain origin-based restrictions are honored. Failure to correctly implement these rules can result in information leakage, cross-site scripting attacks, and the like.
CACHE
MANIFEST", followed by either a U+0020 SPACE character, a
U+0009 CHARACTER TABULATION (tab) character, a U+000A LINE FEED
(LF) character, or a U+000D CARRIAGE RETURN (CR) character.appcache"Fragment identifiers have no meaning with text/cache-manifest resources.
application/microdata+jsonThis registration is for community review and will be submitted to the IESG for review, approval, and registration with IANA.
application/json [JSON]application/json [JSON]application/json [JSON]application/json [JSON]application/microdata+json type asserts that the
resource is a JSON text that consists of an object with a single entry called "items" consisting of an array of entries, each of which consists of an object
with an entry called "id" whose value is a string, an entry called "type" whose value is another string, and an entry called "properties" whose value is an object whose entries each have a value consisting
of an array of either objects or strings, the objects being of the same form as the objects in
the aforementioned "items" entry. Thus, the relevant specifications are
the JSON specification and this specification. [JSON]
Applications that transfer data intended for use with HTML's microdata feature, especially in the context of drag-and-drop, are the primary application class for this type.
application/json [JSON]application/json [JSON]application/json [JSON]Fragment identifiers used with application/microdata+json resources have the same
semantics as when used with application/json (namely, at the time of writing, no
semantics at all). [JSON]
web+ scheme prefixThis section describes a convention for use with the IANA URI scheme registry. It does not itself register a specific scheme. [RFC4395]
web+" followed by one or more letters in the range
a-z.
web+" schemes should use UTF-8 encodings where relevant.web+" schemes. As
such, these schemes must not be used for features intended to be core platform features (e.g.
network transfer protocols like HTTP or FTP). Similarly, such schemes must not store
confidential information in their URLs, such as usernames, passwords, personal information, or
confidential project names.