The vulnerability identified as CVE-2021-42013 is classified as critical, with a CVSS score of 9.8. It impacts the Apache HTTP Server, specifically versions 2.4.49 and 2.4.50. The vulnerability arises from an insufficient fix for CVE-2021-41773, allowing attackers to exploit path traversal techniques to access files outside designated directories. This can potentially lead to remote code execution if the appropriate security configurations are not in place.
Risk to organizations includes unauthorized access to sensitive files and execution of arbitrary code, leading to severe implications for data integrity and availability. Given the high severity and low complexity of the attack vector, organizations should prioritize patching immediately.
As confirmed by threat intelligence sources, this vulnerability is actively exploited in the wild, with a known association with ransomware campaigns. Security teams should assess their environments and take immediate actions to secure vulnerable instances.
In light of these factors, organizations are urged to address this vulnerability as part of their priority patch cycle to mitigate the risks associated with potential exploitation.
Vulnerability Details
CVE-2021-42013 is characterized by a path traversal vulnerability that permits attackers to manipulate URLs and access files that should be restricted. The official CVE description indicates that if files outside the configured directories are not protected by the default 'require all denied' directive, attackers can successfully exploit this vulnerability. The issue is exacerbated when CGI scripts are enabled for the affected paths, leading to potential remote code execution.
With a CVSS score of 9.8, this vulnerability is categorized as critical. The CVSS vector string indicates a network attack vector with low complexity, no required privileges, and no user interaction necessary, making it highly exploitable.
This vulnerability affects Apache HTTP Server versions 2.4.49 and 2.4.50, with no earlier versions impacted. The publication date for CVE-2021-42013 was October 7, 2021.
Technical Analysis
The root cause of this vulnerability is the inadequate handling of path traversal within the Apache HTTP Server, specifically in the context of Alias-like directives. The attack vector is network-based, allowing attackers to send crafted requests that traverse the file system. The attack complexity is low, requiring no special privileges or user interaction.
The impacts on confidentiality, integrity, and availability are all rated as high, meaning that successful exploitation can lead to significant breaches of sensitive information and critical system functions.
Risk & Impact Analysis
Organizations utilizing vulnerable versions of the Apache HTTP Server may face substantial risks, including unauthorized access to sensitive files and the potential for remote code execution. The blast radius is significant, as this vulnerability can affect any web application running on the impacted server versions.
Given the critical nature of this vulnerability and its active exploitation status, organizations must assess their exposure and prioritize remediation. The urgency is underscored by the fact that this vulnerability has been included in the Known Exploited Vulnerabilities (KEV) catalog, indicating its relevance to ongoing threat landscapes.
Exploitation Status
Signal | Status |
|---|---|
Known Exploit | Yes |
Public PoC | Yes |
Actively Exploited | Yes |
Ransomware Use | Yes |
Affected Versions
The affected versions of the Apache HTTP Server are 2.4.49 and 2.4.50. Organizations should ensure that all versions prior to vendor patch are updated to the latest secure version to mitigate this vulnerability.
Mitigation & Remediation
Organizations should apply updates per vendor instructions promptly. For those unable to immediately apply patches, it is recommended to restrict access to sensitive directories and disable CGI scripts where applicable. Additional security hardening measures should be implemented to reduce the attack surface.
For ongoing protection, organizations should consider implementing a penetration testing program to identify and remediate similar vulnerabilities in their systems.
Detection Guidance
Monitoring logs for unusual access patterns and unauthorized file access attempts is crucial. Organizations should look for indicators of compromise related to path traversal attempts and unauthorized CGI script executions.
AppSecure Threat Intelligence Insight
CVE-2021-42013 illustrates a significant risk in software supply chains, highlighting the importance of thorough testing after updates. This vulnerability is a reminder for security teams to regularly audit their systems and ensure that all security patches are applied timely. The trend of vulnerabilities stemming from insufficient patching highlights the need for robust vulnerability management programs.
Organizations looking to strengthen their security posture should consider integrating continuous improvement practices into their security protocols. For further reading on building effective vulnerability management programs, refer to the following resources:
vulnerability management program design and penetration testing methodology can provide strategic insights into enhancing security measures.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
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