Cross-site scripting – Reflected XSS | PortSwigger Lab Note #3

target： Lab URL: https://portswigger.net/web-security/cross-site-scripting/contexts/lab-some-svg-markup-allowed Tools Used: browser Burp suite Vulnerability Summary： Type: Reflected XSS Description: Steps to Exploit： 1.Determine that this is a reflected XSS vulnerability because the input appears directly in the HTML response. 2.Submit the payload alert(1) to test whether script execution is possible. 3.Observe that the <script> tag is blocked, then use Burp Intruder to analyze the filtering mechanism 4.Observe that most payloads return a 400 response, while payloads using tags such as <svg>, <animatetransform>, <title>, and <image> return a 200 response. 5.Select one allowed tag and use Intruder to test which attributes are permitted. 6.Construct a working payload based on the allowed tags and attributes to trigger the XSS. Remediation： The application should implement proper context-aware output encoding to prevent user-supplied data from being interpret