CVE-2022-1276 in mruby
Summary
by MITRE • 04/10/2022
Out-of-bounds Read in mrb_get_args in GitHub repository mruby/mruby prior to 3.2. Possible arbitrary code execution if being exploited.
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Analysis
by VulDB Data Team • 04/13/2022
The vulnerability CVE-2022-1276 represents a critical out-of-bounds read condition within the mruby interpreter library that affects versions prior to 3.2. This flaw exists in the mrb_get_args function which is responsible for parsing function arguments within the mruby scripting environment. The issue stems from insufficient input validation and boundary checking when processing argument lists, allowing attackers to manipulate memory access patterns that exceed allocated buffer limits. The vulnerability is classified under CWE-129 as an Improper Validation of Array Index, which directly relates to the lack of proper bounds checking in argument processing operations.
The technical exploitation of this vulnerability occurs when maliciously crafted mruby scripts are executed, specifically targeting the mrb_get_args function with malformed argument specifications. When the interpreter processes these inputs, it fails to validate array indices properly, leading to memory access violations that can be leveraged for arbitrary code execution. The out-of-bounds read allows attackers to access memory locations beyond the intended array boundaries, potentially exposing sensitive data or enabling control flow manipulation. This vulnerability is particularly dangerous because it can be triggered through normal script execution without requiring special privileges, making it an attractive target for remote code execution attacks.
The operational impact of CVE-2022-1276 extends beyond simple memory corruption, as it can potentially enable attackers to escalate privileges or gain complete system control when exploited in the right context. Systems utilizing mruby for embedded scripting, web applications, or server-side processing are at risk, particularly those that accept untrusted input or execute third-party scripts. The vulnerability aligns with ATT&CK technique T1059.007 for Scripting, specifically targeting the execution of malicious code through interpreted languages. Organizations running vulnerable versions of mruby may experience unauthorized access, data breaches, or complete system compromise, especially in environments where mruby is used for critical operations or as part of larger application frameworks.
Mitigation strategies for CVE-2022-1276 primarily focus on immediate version updates to mruby 3.2 or later, which includes patched implementations of the mrb_get_args function with proper boundary validation. Organizations should conduct comprehensive vulnerability assessments to identify all systems utilizing affected mruby versions and implement patch management procedures to ensure timely updates. Additional defensive measures include input validation controls, sandboxing mechanisms for script execution, and monitoring for suspicious script behavior patterns. The fix addresses the root cause by implementing proper array index validation and bounds checking, preventing the out-of-bounds memory access that previously enabled exploitation. Security teams should also consider implementing runtime protections and code integrity checks to detect and prevent exploitation attempts targeting this vulnerability class.