HTML_ALLOWLIST Function

23.8 HTML_ALLOWLIST Function

The HTML_ALLOWLIST function performs HTML escape on all characters in the input text except the specified allowlist tags. This function can be useful if the input text contains simple html markup but a developer wants to ensure that an attacker cannot use malicious tags for cross-site scripting.

Syntax

APEX_ESCAPE.HTML_ALLOWLIST (
    p_html           IN VARCHAR2,
    p_allowlist_tags IN VARCHAR2 DEFAULT c_html_allowlist_tags )
    return VARCHAR2 deterministic;

Parameters

Table 23-8 HTML_ALLOWLIST Parameters

Parameter	Description
`p_html`	The text string that is filtered.
`p_allowlist_tags`	The comma separated list of tags that stays in `p_html`.

Example

This example shows how to use HTML_ALLOWLIST to remove unwanted html markup from a string, while preserving allowlisted tags.

BEGIN
     sys.htp.p(apex_escape.html_allowlist(
         '<h1>Hello<script>alert("XSS");</script></h1>'));
END;