Discourse XSS and Resource Exhaustion Flaws

Discourse versions prior to 3.4.4 (stable), 3.5.0.beta5 (beta), and 3.5.0.beta6-dev (tests-passed) contain a critical vulnerability where Codepen is included in the default `allowed_iframes` site setting and can auto-execute arbitrary JavaScript within the iframe scope, enabling unauthenticated remote code execution. With a CVSS score of 9.8 and network-accessible attack vector requiring no privileges or user interaction, this vulnerability poses severe risk to all default Discourse installations and should be prioritized for immediate patching.

Denial-of-service vulnerability in Discourse that allows unauthenticated remote attackers to reduce the availability of a Discourse instance by sending malicious URLs in private messages to bot users. The vulnerability affects Discourse versions prior to 3.4.4 (stable), 3.5.0.beta5 (beta), and 3.5.0.beta6-dev (tests-passed), with a CVSS 7.5 rating indicating high severity. No known public exploits or workarounds are currently available, but patches have been released.

A remote code execution vulnerability in Discourse (CVSS 7.1). High severity vulnerability requiring prompt remediation.