Symfony 4.4.0 to 4.4.3 and 5.0.0 to 5.0.4 versions of the Symfony ErrorHandler component are affected by this security issue.
The issue has been fixed in Symfony 4.4.4 and 5.0.4.
When ErrorHandler
renders an exception HTML page, it uses un-escaped properties from the related Exception class to render the stacktrace. The security issue comes from the fact that the stacktraces were also displayed in non-debug
environments.
The ErrorHandler
class now escapes all properties coming from the related Exception, and the stacktrace is not displayed anymore in non-debug
environments.
The patches for this issue are available here and here for 4.4 branch.
I would like to thank Bojan Zdrnja for reporting & Yonel Ceruto and Jérémy Derussé for fixing the issue.
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