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fix(compiler): add mglyph src to security schema to prevent XSS#67113

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ZeroXJacks wants to merge 2 commits intoangular:mainfrom
ZeroXJacks:patch-1
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fix(compiler): add mglyph src to security schema to prevent XSS#67113
ZeroXJacks wants to merge 2 commits intoangular:mainfrom
ZeroXJacks:patch-1

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@ZeroXJacks
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This PR adds the src attribute of the MathML mglyph element to the SECURITY_SCHEMA.

Problem: Currently, mglyph[src] is not mapped to any SecurityContext, causing it to default to SecurityContext.NONE. This allows an attacker to bypass Angular's DomSanitizer and execute arbitrary JavaScript using javascript: URIs.

Solution: By adding mglyph|src to the schema, Angular will correctly sanitize the attribute as a URL context, aligning it with how mglyph[href] and mglyph[xlink:href] are handled.

Added missing 'src' attribute for 'mglyph' to enhance security against XSS.
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Added missing attribute 'mglyph|src' for security enhancement to prevent XSS.
Comment on lines +13 to +17
// =========== S T O P - S T O P - S T O P - S T O P - S T O P - S T O P ===========
// =================================================================================================
// =================================================================================================
//
// DO NOT EDIT THIS LIST OF SECURITY SENSITIVE PROPERTIES WITHOUT A SECURITY REVIEW!
// DO NOT EDIT THIS LIST OF SECURITY SENSITIVE PROPERTIES WITHOUT A SECURITY REVIEW!
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Can you please revert the changes here.

@alan-agius4
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Thanks for the PR, but mglyph|src is intentionally not in the list. mglyph|src is not a valid trigger for javascript: URIs.

@ZeroXJacks
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Hi @alan-agius4 @JeanMeche,

Thank you for the quick review. While I understand that current mainstream browsers may not execute javascript: URIs via the mglyph[src] attribute, I believe its omission from the SECURITY_SCHEMA represents a Security Context Omission that contradicts Angular's "Secure by Default" architecture for the following reasons:
Architectural Inconsistency: Angular already explicitly sanitizes mglyph[href] and mglyph[xlink:href] (mapped to SecurityContext.URL). From a framework perspective, src and href in MathML serve identical purposes: fetching external resources. Treating one as a security-sensitive URL and the other as SecurityContext.NONE creates an unpredictable security boundary for developers.
Defense in Depth: Angular’s DomSanitizer historically sanitizes attributes even if they aren't currently exploitable in all browsers (e.g., certain SVG attributes). This is to protect against:
Legacy/Niche Browsers: Users on older or non-standard browsers where MathML implementation might be less restrictive.

Future Browser Changes: If a browser engine decides to unify the handling of src and href in MathML, Angular apps will be zero-day vulnerable because the framework explicitly "trusted" the attribute.

Bypass of Developer Intent: When a developer uses [attr.src], they rely on Angular to be the first line of defense. The fact that javascript:alert(1) is rendered raw without the unsafe: prefix (unlike href) proves a failure in the framework's sanitization logic, regardless of the browser's final execution policy.

Proof of Inconsistency (Unit Test):

I request a re-review of this PR not as a fix for an immediate Chrome exploit, but as a necessary patch to ensure Sanitization Consistency and robust Defense in Depth within the compiler's security schema.

Best regards,
ZeroXJacks

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