CVE-2021-27850: Remote Code Execution in Apache Tapestry
Summary
CVE-2021-27850: Remote code execution in Apache Tapestry. Affects org.apache.tapestry:tapestry-core across 2 version ranges.
>= 5.4.0, < 5.6.3
>= 5.7.0, < 5.7.1
Fixed in 5.6.3 or 5.7.1, depending on the release line you run. How to fix ↓
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Background
Apache Tapestry is an open-source component-oriented web application framework for Java. It provides a powerful and flexible programming model for building dynamic web applications. The vulnerability identified as CVE-2021-27850 affects versions 5.4.5, 5.5.0, 5.6.2, and 5.7.0 of Apache Tapestry. This vulnerability allows unauthenticated remote code execution, potentially leading to a compromise of the affected system.
Vulnerability Detail
The vulnerability is a bypass of the fix for CVE-2019-0195. Prior to the fix, it was possible to download arbitrary class files from the classpath by providing a crafted asset file URL. The fix introduced a blacklist filter to check for specific file extensions. However, this blacklist solution can be bypassed by appending a / at the end of the URL. This allows the loading of the desired class file into the response, which may contain sensitive information such as HMAC secret keys. With knowledge of the secret key, an attacker can sign a Java gadget chain to achieve remote code execution.
How To Fix
Latest published version: 5.9.1 as of 22 Oct 2026
Upgrading to it may include breaking changes; the versions below are the minimum fixed release for this vulnerability.
If you can't move to the latest
The minimum fixed version depends on the release line you run.
-
>= 5.4.0, < 5.6.35.6.3 -
>= 5.7.0, < 5.7.15.7.1
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Workaround
There is no specific workaround provided for this vulnerability. It is crucial to apply the recommended fix by upgrading to the patched versions.
Conclusion
The identified vulnerability in Apache Tapestry (CVE-2021-27850) allows unauthenticated remote code execution, posing a significant risk to affected systems. It is essential to upgrade to the patched versions to mitigate this vulnerability. For further support on vulnerability remediation, please contact DevNack.com.
See every vulnerability recorded for org.apache.tapestry:tapestry-core →
FAQ
Apache Tapestry is an open-source component-oriented web application framework for Java. It provides a powerful and flexible programming model for building dynamic web applications.
The vulnerability affects versions 5.4.5, 5.5.0, 5.6.2, and 5.7.0 of Apache Tapestry.
The vulnerability allows unauthenticated remote code execution, potentially leading to a compromise of the affected system.
To fix this vulnerability, it is recommended to upgrade to the patched versions: 5.6.3 or later for Apache Tapestry 5.4.0 to 5.6.2, and 5.7.1 or later for Apache Tapestry 5.7.0.
There is no specific workaround provided for this vulnerability. It is crucial to apply the recommended fix by upgrading to the patched versions.
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