CVE-2020-1959: Expression Language Injection in Apache Syncope
Summary
CVE-2020-1959: Expression Language Injection in Apache Syncope. Affects org.apache.syncope:syncope-core versions < 2.1.6. Fixed in 2.1.6. How to fix ↓
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Background
Apache Syncope is an open-source system for managing digital identities in enterprise environments. It provides features such as user and role management, access control, and workflow automation. The vulnerability identified in Apache Syncope prior to version 2.1.6 is an Expression Language (EL) Injection. This vulnerability allows attackers to inject arbitrary Java EL expressions, leading to an unauthenticated Remote Code Execution (RCE) vulnerability. Apache Syncope utilizes Java Bean Validation (JSR 380) custom constraint validators, which support different types of interpolation, including Java EL expressions. By injecting arbitrary data in the error message template, an attacker can execute arbitrary Java code.
Vulnerability Detail
The Expression Language Injection vulnerability in Apache Syncope allows attackers to inject arbitrary Java EL expressions, leading to unauthenticated Remote Code Execution (RCE). This vulnerability arises from the support for different types of interpolation, including Java EL expressions, in the custom constraint violation error messages of Apache Syncope. By injecting arbitrary data in the error message template, an attacker can execute arbitrary Java code. This can result in the compromise of the affected system, unauthorized access, data breaches, and potential damage to the entire enterprise environment.
How To Fix
Latest published version: 4.1.3 as of 23 Oct 2026
Upgrading to it may include breaking changes; the version below is the minimum fixed release for this vulnerability.
If you need the minimum change
2.1.6
This is the first release that contains the fix.
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Workaround
As a temporary workaround, users can disable the usage of Java EL expressions in the error message templates. This can be achieved by modifying the configuration of Apache Syncope to disallow the interpolation of Java EL expressions. However, it is important to note that this workaround may impact the functionality of certain features that rely on the usage of Java EL expressions. Therefore, it is strongly recommended to apply the official fix by upgrading to Apache Syncope version 2.1.6 or later.
Conclusion
The Expression Language Injection vulnerability in Apache Syncope poses a significant risk to the security and integrity of enterprise environments. It allows attackers to execute arbitrary Java code, potentially leading to unauthorized access, data breaches, and system compromise. To mitigate this vulnerability, it is crucial to upgrade Apache Syncope to version 2.1.6 or later. Users can also utilize Vulert, a tool that monitors and alerts in real-time for open-source vulnerabilities, to check if their application is affected by this vulnerability. For further support on vulnerability remediation, you can contact DevNack.com.
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FAQ
Apache Syncope is an open-source system for managing digital identities in enterprise environments. It provides features such as user and role management, access control, and workflow automation.
The vulnerability allows attackers to execute arbitrary Java code, leading to unauthenticated Remote Code Execution (RCE). This can result in the compromise of the affected system, unauthorized access, data breaches, and potential damage to the entire enterprise environment.
To fix this vulnerability, it is recommended to upgrade Apache Syncope to version 2.1.6 or later. This version includes the necessary patches to mitigate the Expression Language Injection vulnerability.
As a temporary workaround, users can disable the usage of Java EL expressions in the error message templates. However, this may impact the functionality of certain features that rely on the usage of Java EL expressions.
For more information about this vulnerability, you can refer to the official CVE-2020-1959 advisory or contact the Apache Syncope community.
References
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