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CVE-2018-19131 is a cross-site scripting vulnerability in Squid (before 4.4) in the generation of HTTP(S) error pages for TLS/X.509 certificate validation failures. A malicious HTTPS server can present a crafted X.509 certificate such that, when Squid produces the certificate-error response page to the client, attacker-controlled content is embedded into the HTML error page, enabling injection of arbitrary HTML/JavaScript in the client context.
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1 valid exploit after Mallory filtered fakes, detection scripts, and README-only repos.
This repository is a proof-of-concept exploit for CVE-2018-19131, a cross-site scripting (XSS) vulnerability in Squid Proxy's error page handling when SSL bumping is enabled. The exploit demonstrates how a malicious certificate with a script tag in the commonName field can cause arbitrary JavaScript to execute in the browser when a user encounters a Squid error page. The repository includes Docker and Docker Compose files to build and run a vulnerable Squid 3.5.27 instance, as well as an Nginx server serving a crafted certificate. The main exploit mechanism is the injection of a script payload into the certificate, which is then reflected in the error page and executed by the browser. The structure includes configuration files for Squid and Nginx, a shell script to generate certificates, and documentation illustrating the vulnerability. The exploit is network-based, requiring the victim to use the vulnerable proxy and visit a malicious site. No weaponized or automated exploitation is present; this is a clear, educational proof-of-concept.
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