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[SEC-021][All] Validate intent:// browser_fallback_url scheme #3681

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[SEC-021][All] Validate intent:// browser_fallback_url scheme #3681

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5 changes: 4 additions & 1 deletion libs/pandautils/src/main/java/com/instructure/pandautils/views/CanvasWebView.kt
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Original file line number Diff line number Diff line change
Expand Up @@ -486,7 +486,10 @@ class CanvasWebView @JvmOverloads constructor(
//try to find fallback url
val fallbackUrl = appIntent.getStringExtra("browser_fallback_url")
if (fallbackUrl != null) {
view.loadUrl(fallbackUrl, extraHeaders)
val fallbackScheme = Uri.parse(fallbackUrl).scheme?.lowercase()
if (fallbackScheme == "http" || fallbackScheme == "https") {
view.loadUrl(fallbackUrl, extraHeaders)
}

@claude claude Bot May 5, 2026

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When fallbackScheme is neither "http" nor "https", the fallback URL is silently dropped and return true consumes the navigation event — the user gets a broken experience with no indication of what happened. Consider adding a warning log here to aid future debugging:

} else {
    Log.w("CanvasWebView", "Blocked unsafe fallback URL scheme: $fallbackScheme")
}

This doesn't need to be user-visible, but a logcat entry would make it much easier to diagnose reports of broken intent-fallback navigation in the field.

return true
}
} catch (e: URISyntaxException) {
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