Reflected XSS on MercadoLibre
Reflected XSS vulnerability in MercadoLibre's q parameter that allowed an attacker to inject JavaScript code and obtain session cookies.
Antecedentes
MercadoLibre is the leading e-commerce platform in Latin America.
Description
The application contained a reflected XSS vulnerability that allowed attackers to inject JavaScript code. An attacker could send a malicious URL to their victim and obtain their session cookies. The vulnerable parameter was q via the GET method, exploitable with "recent" or "archived" type values.
Business impact
The impact of the discovered vulnerability is rated as medium-critical, as if the user has an active session, their current cookies could be captured by the attacker.
Sistemas afectados
MercadoLibre website (myaccount.mercadolibre.com.ar)
Solución
Proper escaping of untrusted data according to the HTML context, positive server-side validation, auto-sanitizing libraries (OWASP AntiSamy), and implementation of Content Security Policy (CSP) are recommended.
Calendario de divulgación
References
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