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Apache Struts 2 Documentation
S2-018
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## Summary

Broken Access Control Vulnerability in Apache Struts2

Who should read this | All Struts 2 developers and users
Impact of vulnerability | Permissions, Privileges, and Access Controls
Maximum security rating | Important
Recommendation | Developers should immediately upgrade to Struts 2.3.15.3
Affected Software | Struts 2.0.0 - Struts 2.3.15.2
Reporter | Zhu Gang, Zhang Jin, Huawei PSIRT
CVE Identifier | CVE-2013-4310

## Problem

The Struts 2 action mapping mechanism supports the special parameter prefix action: which is intended to help with attaching navigational information to buttons within forms.

In Struts 2 before 2.3.15.3, under certain conditions this can be used to bypass security constraints. More details will available later on when the patch will be widely adopted.

## Solution

In Struts 2.3.15.3 the action mapping mechanism was changed to avoid circumventing security constraints. Two additional constants were introduced to steer behaviour of DefaultActionMapper:

- struts.mapper.action.prefix.enabled - when set to false support for "action:" prefix is disabled, set to false by default
- struts.mapper.action.prefix.crossNamespaces - when set to false, actions defined with "action:" prefix must be in the same namespace as current action

Backward Compatibility

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After upgrading to Struts 2.3.15.3, applications using the "action:" will stop working. You can use above constants to steer that behaviour.

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It is strongly recommended to upgrade to Struts 2.3.15.3, which contains the corrected Struts2-Core library.