CVE-2020-27221 in OpenJ9
Summary
by MITRE • 01/21/2021
In Eclipse OpenJ9 up to version 0.23, there is potential for a stack-based buffer overflow when the virtual machine or JNI natives are converting from UTF-8 characters to platform encoding.
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Analysis
by VulDB Data Team • 10/15/2024
The vulnerability identified as CVE-2020-27221 affects the Eclipse OpenJ9 runtime environment, specifically versions up to 0.23, where a stack-based buffer overflow can occur during character encoding conversion operations. This flaw manifests when the virtual machine or JNI native components process UTF-8 character sequences and attempt to convert them to platform-specific encoding formats. The buffer overflow represents a critical security weakness that could potentially allow attackers to execute arbitrary code or cause system instability.
The technical root cause of this vulnerability lies in inadequate bounds checking during the UTF-8 to platform encoding conversion process within the OpenJ9 runtime. When processing character data, the system fails to properly validate the length of input UTF-8 sequences against the allocated buffer space in the stack memory. This oversight creates an exploitable condition where maliciously crafted UTF-8 input can exceed the allocated buffer boundaries, leading to memory corruption. The vulnerability specifically impacts the runtime's handling of character encoding conversions, which are fundamental operations in Java applications that process text data from various sources.
Operationally, this vulnerability poses significant risks to systems running affected versions of Eclipse OpenJ9, particularly in environments where applications process untrusted input data through JNI interfaces or direct virtual machine operations. Attackers could exploit this flaw by providing specially crafted UTF-8 encoded input that triggers the buffer overflow condition during encoding conversion. The potential impact includes arbitrary code execution with the privileges of the running Java application, denial of service conditions, or information disclosure. Given that OpenJ9 is used in various enterprise applications and server environments, the exploitation of this vulnerability could affect critical business systems and infrastructure components.
The vulnerability aligns with CWE-121 Stack-based Buffer Overflow, which specifically addresses buffer overflows occurring in stack memory regions. From an adversarial perspective, this flaw maps to ATT&CK technique T1059.007 Command and Scripting Interpreter: Unix Shell, as exploitation could enable attackers to execute malicious code through compromised Java processes. The attack surface is particularly concerning in web applications, enterprise servers, and containerized environments where OpenJ9 is deployed. Organizations should prioritize patching affected systems and implementing monitoring for suspicious encoding conversion activities. The recommended mitigation strategy includes upgrading to Eclipse OpenJ9 version 0.24 or later, which contains the necessary fixes for proper buffer bounds checking during character encoding operations. Additionally, input validation and sanitization measures should be implemented at application layers to reduce the risk of exploitation through malformed UTF-8 sequences.