CVE-2021-43519 is a medium-severity vulnerability affecting the Lua Interpreter versions 5.1.0 to 5.4.4. This vulnerability allows attackers to perform a Denial of Service via a crafted script file, exploiting a stack overflow in the lua_resume function of ldo.c. The vulnerability's CVSS score is 5.5, indicating a medium level of risk. Organizations utilizing affected versions of Lua are urged to assess their exposure and take appropriate action.
The real-world impact of this vulnerability is significant, as it can lead to system outages and disruptions in service availability. Attackers could exploit this vulnerability by executing specially crafted scripts, which could cause the Lua interpreter to crash. Given the potential for service interruptions, organizations should prioritize addressing this vulnerability in their patch management processes.
Currently, there are no known exploits available in the wild for this vulnerability, and it has not been included in the Known Exploited Vulnerabilities (KEV) catalog. However, the lack of known exploits does not diminish the urgency of remediation, as the risk remains if systems are not updated or patched.
Organizations should plan to address this vulnerability promptly to mitigate any potential disruptions. It is advisable to review the affected systems and implement patches or workarounds as necessary to ensure continued service availability.
Vulnerability Details
The vulnerability stems from a stack overflow in the lua_resume function located in ldo.c of the Lua Interpreter. As a result, it allows attackers to craft specific inputs that can crash the interpreter, leading to Denial of Service. The CVSS score of 5.5 classifies this vulnerability as medium severity, indicating a significant impact on availability.
Affected versions include Lua Interpreter from 5.1.0 to 5.4.4. The vulnerability affects multiple platforms, specifically those utilizing the Fedora distribution of Linux.
It is crucial for users and administrators to be aware of the CWE classification linked to this vulnerability, which is CWE-674: Uncontrolled Recursion. The publication date of this vulnerability was November 9, 2021, and it has been marked as modified due to new findings.
Technical Analysis
The root cause of CVE-2021-43519 is a stack overflow that occurs when the lua_resume function is invoked with a crafted input. This leads to the interpreter consuming excessive stack memory, ultimately resulting in a crash. The attack vector is local, and the attack complexity is low, requiring no privileges for execution but necessitating user interaction to trigger the vulnerability.
Once triggered, the availability impact is high, as the Lua interpreter will become unresponsive. The vulnerability does not affect confidentiality or integrity, making it primarily a service availability concern.
Risk & Impact Analysis
The deployment risk associated with CVE-2021-43519 is significant for organizations relying on the Lua Interpreter, especially those using it in critical applications. The potential for service disruption poses a direct threat to business continuity. As Lua is often integrated into larger applications, the blast radius of an exploit could affect multiple components, leading to widespread service outages.
Given the medium CVSS score and the current lack of active exploitation, organizations should prioritize patching this vulnerability in their upcoming maintenance cycles. The risk of future exploitation exists, and organizations should be proactive in their remediation efforts to maintain system integrity and availability.
Signal | Status |
|---|---|
Known Exploit | No |
Public PoC | No |
Actively Exploited | No |
Ransomware Use | No |
Affected Versions
All versions of Lua Interpreter from 5.1.0 to 5.4.4, as well as Fedora version 35, are affected by this vulnerability. Users are urged to upgrade their systems to mitigate potential risks.
Mitigation & Remediation
To mitigate the risks associated with CVE-2021-43519, organizations should apply the latest patches for the Lua Interpreter. Specifically, users should upgrade to versions that are above 5.4.4 to ensure they are not vulnerable. In instances where immediate patching is not feasible, consider implementing configuration hardening strategies and network controls to limit exposure.
For comprehensive security assessments, organizations may consider utilizing application security assessments to identify any additional weaknesses in their systems.
Detection Guidance
Organizations should monitor logs for any unusual activity related to the Lua interpreter and look for behavioral anomalies that could indicate attempts to exploit this vulnerability. Additionally, network signatures that identify unusual script files being executed could provide early warning signs of an attempted attack.
AppSecure Threat Intelligence Insight
CVE-2021-43519 represents a critical point of attention for organizations using Lua in their applications. The low EPSS score indicates a lower probability of exploitation but emphasizes the need for vigilance in maintaining security best practices. Security teams should learn from this vulnerability and reinforce their testing methodologies, ensuring that similar issues are addressed proactively.
For further insights on vulnerability management strategies, organizations can refer to the following resources: vulnerability management programs, penetration testing methodologies, and web application security testing to strengthen their defenses.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
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