Analysis · curated 13 Sep 2026
PortSwigger Lab Walkthrough: Exploiting insecure output handling in LLMs
First reported youtube.com
Coverage timeline
Single-source analysis — first reported, latest, and curated coincide.
Why it matters
Insecure output handling in LLM-driven interfaces lets attacker-planted content (e.g. comments retrieved via function calls) execute as XSS in a victim's browser, a real risk for defenders deploying LLM chat features that render tool output.
A video walkthrough by Siberci Aslan Akbey (umay_samli) covers the PortSwigger Web Security Academy lab on exploiting insecure output handling in LLMs, showing how a malicious product comment containing an XSS/iframe payload gets rendered unsanitized in the LLM chat interface, enabling DOM manipulation and unauthorized account deletion. The demonstration is performed entirely in the intentionally vulnerable PortSwigger lab environment.