Apache Dubbo <2.6.10/2.7.10: Telnet Handler RCE via Bean Manipulation
CVE-2021-32824 Published on January 3, 2023
Regular expression Denial of Service in MooTools
Apache Dubbo is a java based, open source RPC framework. Versions prior to 2.6.10 and 2.7.10 are vulnerable to pre-auth remote code execution via arbitrary bean manipulation in the Telnet handler. The Dubbo main service port can be used to access a Telnet Handler which offers some basic methods to collect information about the providers and methods exposed by the service and it can even allow to shutdown the service. This endpoint is unprotected. Additionally, a provider method can be invoked using the `invoke` handler. This handler uses a safe version of FastJson to process the call arguments. However, the resulting list is later processed with `PojoUtils.realize` which can be used to instantiate arbitrary classes and invoke its setters. Even though FastJson is properly protected with a default blocklist, `PojoUtils.realize` is not, and an attacker can leverage that to achieve remote code execution. Versions 2.6.10 and 2.7.10 contain fixes for this issue.
Vulnerability Analysis
CVE-2021-32824 is exploitable with network access, and does not require authorization privileges or user interaction. This vulnerability is considered to have a low attack complexity. An automatable proof of concept (POC) exploit exists. The potential impact of an exploit of this vulnerability is considered to be critical as this vulnerability has a high impact to the confidentiality, integrity and availability of this component.
Weakness Type
What is a Marshaling, Unmarshaling Vulnerability?
The application deserializes untrusted data without sufficiently verifying that the resulting data will be valid.
CVE-2021-32824 has been classified to as a Marshaling, Unmarshaling vulnerability or weakness.
Products Associated with CVE-2021-32824
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Affected Versions
Apache Dubbo:- Version 2.6.10 and below 2.6.10 is affected.
- Version 2.7.10 and below 2.7.10 is affected.
- Version 2.7.0 and below 2.7.0* is affected.
Exploit Probability
EPSS (Exploit Prediction Scoring System) scores estimate the probability that a vulnerability will be exploited in the wild within the next 30 days. The percentile shows you how this score compares to all other vulnerabilities.