Disable embedded HTML code [Updated in Security Center 1.3]

  • Release version: Xanadu
  • Updated May 15, 2026
  • 2 minutes to read
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    Summary of Disable embedded HTML code [Updated in Security Center 1.3]

    Theglide.ui.security.allowcodetagsystem property controls whether HTML code embedded using the [code] tag is rendered in journal fields and forms within ServiceNow. Rendering HTML in these fields can expose your instance to cross-site scripting (XSS) attacks, where malicious scripts may execute in users’ browsers and compromise session data and sensitive information.

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    Key Features

    • Disabling HTML rendering: Setting glide.ui.security.allowcodetag to false completely disables the rendering of HTML from [code] tags in journal fields, encoding the HTML instead to prevent script execution and mitigate XSS risks.
    • Preserving HTML rendering without scripts: If disabling HTML rendering breaks functionality that depends on it, you can keep glide.ui.security.allowcodetag set to true but set glide.ui.security.codetag.allowscript to false. This allows HTML rendering while preventing any embedded scripts from executing, reducing risk while maintaining usability.
    • ServiceNow AI Platform protections: The AI Platform applies escaping and encoding to inputs to reduce injection and scripting attacks, but [code] tags can still render HTML unless controlled by these properties.

    Key Outcomes

    • Improved security posture against XSS by controlling HTML rendering in journal fields, protecting user sessions and sensitive data.
    • Flexibility to balance security and functionality by choosing whether to disable HTML rendering entirely or only disable script execution within HTML.
    • Awareness that disabling HTML rendering may cause HTML tags to appear in journal fields, potentially impacting user experience and functionality.

    Practical Considerations for ServiceNow Customers

    • For maximum security, set glide.ui.security.allowcodetag to false in the Instance Security Center to block all HTML rendering from [code] tags.
    • If your instance relies on HTML rendering in journal fields, keep glide.ui.security.allowcodetag true but disable scripts with glide.ui.security.codetag.allowscript false.
    • Understand that even with script disabling, some residual risk remains because HTML rendering is still allowed.
    • Monitor the impact on functionality and user interaction, especially if journal fields are heavily used for formatted content.

    Use the glide.ui.security.allow_codetag property to disable support for embedding HTML code created using the [code] tag.

    Disable support for displaying HTML code embedded using the [code] tag. This tag allows rendered HTML to display in journal fields and may lead to cross-site scripting (XSS) attacks. These attacks can enable foreign scripts to execute on a user session in the logged in browser's context. Attackers can use these scripts to steal session information and sensitive data. The HTML language was not designed to separate script from formatting, so allowing user-controlled HTML in any system has inherent risk.

    If setting glide.ui.security.allow_codetag to false disrupts instance functionality, for example, if your instance uses a feature that relies on HTML rendering in journal fields, you can maintain a compliant security posture by keeping glide.ui.security.allow_codetag set to true and setting glide.ui.security.codetag.allow_script to false. This change disables script execution within [code] tags while preserving HTML rendering. Note that this approach carries some residual risk, as it relies on sanitizing all known script conventions within HTML rather than prohibiting HTML code tags entirely.

    Set the glide.ui.security.allow_codetag system property to false to completely prohibit journal fields and forms from displaying rendered HTML.

    The ServiceNow AI Platform mitigates many injection and cross-site attacks by implementing escaping and encoding techniques. As a result, users can't write/submit HTML formatted inputs for journal fields. But journal fields can render text enclosed within code tags as HTML.
    • However, there is an associated security risk. If set to true, malicious users can write harmful HTML JS code that may be executed on a different client browser after rendering of journal fields.
    • Set this property to false so that administrators can prevent journal fields from rendering HTML code by disabling support for the [code] tag.

    More information

    Attribute Description
    Property name glide.ui.security.allow_codetag
    Configuration type System Properties (/sys_properties_list.do)
    Category Validation, sanitization, and encoding
    Configure in Instance Security Center Yes
    Purpose Protect against cross-site scripting and malicious script execution
    Recommended value false
    Default value true
    Security risk rating 4.2
    Functional impact This remediation enforces HTML encoding to occur on the UI and renders the encoded results to the user.

    This property is set to true by default. In this state, your instance displays rendered HTML in journal fields and forms.

    If this property is set to false, HTML is not rendered properly and HTML tags may appear in journal fields on forms. It can have an adverse impact on functionality, and on user interactions with the resulting data.

    If this property negatively affects functionality, set glide.ui.security.codetag.allow_script to false to disable script execution within [code] tags while preserving HTML rendering.
    Security risk (Medium) Input validation must occur in the application to defend against cross-site scripting attacks. These attacks enable foreign scripts to execute on a user session in the logged in browser's context. Attackers can use it to steal session information and sensitive data.