Highlights
Auth Bypass: 2 prior fixes. Scrutinize any change in this area.
EventListener/SecurityListener.php: most-fixed (2 issues). Treat as high-risk during review.
2 high-severity fixes in this history; regressions here are high-impact.
Recurring patterns
The bug types that recur here, drawn from past fixes, not open vulnerabilities.
Auth Bypass: User-supplied request attributes can overwrite reserved security expression variables (like 'user' or 'role'), allowing malicious actors to manipulate context variables and completely bypass security expression checks.
Auth Bypass: Incompatibility between Symfony 3.4 Role objects and the security expression evaluator could cause checks to silently fail or pass incorrectly, necessitating normalization of roles to string representations.