CVE-2020-5275: All "access_control" rules are required when a firewall uses the unanimous strategy

Affected versions

Symfony 4.4.0 to 4.4.6 and 5.0.0 to 5.0.6 versions of the Symfony ErrorHandler component are affected by this security issue.

The issue has been fixed in Symfony 4.4.7 and 5.0.7.

Description

On Symfony before 4.4.0, when a Firewall checks an access control rule (using the unanimous strategy), it iterates over all rule attributes and grant access only if all calls to the accessDecisionManager decide to grant access.

As of Symfony 4.4.0, a bug was introduced that prevents the check of attributes as soon as accessDecisionManager decide to grant access on one attribute.

Resolution

The accessDecisionManager is now called with all attributes at once, allowing the unanimous strategy being applied on each attribute.

The patch for this issue is available here for the 4.4 branch.

Credits

I would like to thank Antonio J. GarcĂ­a Lagar for reporting & Robin Chalas for fixing the issue.

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CVE-2020-5275: All "access_control" rules are required when a firewall uses the unanimous strategy symfony.com/blog/cve-2020-5275-all-access-control-rules-are-required-when-a-firewall-uses-the-unanimous-strategy

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