Potential fix for code scanning alert no. 33: Client-side cross-site scripting

[Dargon789]

Potential fix for https://github.com/Dargon789/mempool/security/code-scanning/33

To fix the cross-site scripting vulnerability, ensure that only safe, expected values for the redirection target are used, and never directly interpolate unsanitized user input (such as params.next) into URLs or location changes. Since only known path strings are acceptable, we should always use the trusted value from the path array rather than the raw params.next. Specifically, in the line window.location.replace(${params.next}?next=${nextPath}), we should replace params.next with the trusted path[index] value that was matched from the array (or, to be extra safe, use nextPath). This avoids using raw user input and prevents injection vulnerabilities.

Changes should be made in frontend/src/app/shared/common.utils.ts, by editing the implementation of handleDemoRedirect so that only safe, trusted strings from the predefined array are used in the location replacement.

No new methods or external dependencies are required.

Suggested fixes powered by Copilot Autofix. Review carefully before merging.

Summary by Sourcery

Bug Fixes:

• Change handleDemoRedirect to use the trusted path[index] value in window.location.replace rather than params.next

[sourcery-ai]

Reviewer's guide (collapsed on small PRs)

Reviewer's Guide

Replaces direct use of unsanitized params.next in the redirect URL with the trusted value from a predefined path array in handleDemoRedirect, closing the XSS hole by only interpolating known-safe strings.

Sequence diagram for safe redirection in handleDemoRedirect

sequenceDiagram
participant User as actor User
participant Route as ActivatedRoute
participant Router as Router
participant Utils as common.utils.ts
User->>Route: Navigates with next param
Route->>Utils: handleDemoRedirect(route, router)
Utils->>Utils: Validate params.next against path array
alt params.next is valid
Utils->>Utils: Compute nextPath
Utils->>Browser: window.location.replace(`${path[index]}?next=${nextPath}`) after 15s
else params.next is invalid
Utils->>Utils: No redirect
end

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File-Level Changes

Change	Details	Files
Sanitize redirect target by swapping raw user input for a trusted path value	Replaced ${params.next} with ${path[index]} in window.location.replace Retained nextPath selection logic while restricting redirection to known paths	frontend/src/app/shared/common.utils.ts

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