1sealsemantic last-mile verification

Research / Finding

JSON injection in Mini App custom method response enables arbitrary JavaScript execution in WebAppWebView

F-TELEGRAM-JSBRIDGE-001

Public snapshot: 26 Sep 2026. Status, releases and attribution belong to each source below; none is inferred from another record.

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Recorded evidence

—score not recorded
TelegramMessenger/Telegram-iOSReported fixTelegramMessenger/Telegram-iOS

JSON injection in Mini App custom method response enables arbitrary JavaScript execution in WebAppWebView

fixed publicly
details
Finding IDs
F-TELEGRAM-JSBRIDGE-001
Status
fixed publicly
Reported via
Telegram security contact
Note
accepted as LOW. public fix commit 687cefb2914539e2a42d3a10e91fe4ce1c7fbf7f on 2026-02-25 serializes the custom method result through JSONSerialization before sendEvent; the fix is present in release-12.5.

F-TELEGRAM-JSBRIDGE-001: Code / markup injection. Bridge result data is interpolated into JavaScript instead of serialized. Reviewed 24 Sep 2026. Mechanism assessed by 1seal.

Mechanism source for F-TELEGRAM-JSBRIDGE-001

Security area (1seal assessment): Semantics. Bridge result data is interpolated into JavaScript instead of serialized. Reviewed 24 Sep 2026.

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