CVE-2021-36159 is a critical vulnerability affecting FreeBSD's libfetch, an essential component in various tools, including apk-tools and xbps. Specifically, this vulnerability allows mishandling of numeric strings for the FTP and HTTP protocols. The issue arises from the FTP passive mode implementation which permits an out-of-bounds read due to improper checks when parsing relevant numbers into address bytes. The strtol function does not verify if the line terminates prematurely, leading the for-loop condition to evaluate the '\0' terminator one byte too late.
With a CVSS score of 9.1, this vulnerability is classified as critical, indicating that it poses a severe risk to organizations utilizing affected versions of libfetch. The vulnerability's high severity stems from its network attack vector, low attack complexity, and the potential for significant confidentiality and availability impacts. Given the nature of this flaw, organizations using FreeBSD should prioritize remediation efforts.
The exploitation status for CVE-2021-36159 indicates that there are no known public exploits or proof of concepts available at this time. However, the critical nature of the vulnerability necessitates immediate attention to patching or updating systems to mitigate risks. Organizations should be aware that the potential for exploitation exists, especially given the common use of libfetch in various applications.
Organizations should prioritize patching immediately to protect against potential exploitation of this vulnerability. By ensuring that systems are updated to the latest versions of libfetch, organizations can significantly reduce their exposure to this critical risk.
Vulnerability Details
The official CVE description highlights the root cause of the vulnerability, which allows for an out-of-bounds read due to the mishandling of numeric strings during FTP and HTTP operations. The vulnerability affects libfetch versions prior to July 26, 2021.
The vulnerability is classified under CWE-125, indicating improper handling of buffer boundaries. The implications of this flaw can lead to unauthorized data access, making it a significant threat to confidentiality.
Technical Analysis
The root cause of CVE-2021-36159 is the lack of proper validation in the parsing logic of numeric strings. Attackers can exploit this vulnerability by sending specially crafted input during FTP or HTTP requests, resulting in an out-of-bounds read. The attack vector is network-based, requiring no privileges or user interaction, which makes the vulnerability particularly dangerous.
The attack complexity is low, as it does not require any specialized skills or extensive knowledge of the underlying system. The confidentiality impact is rated high, indicating that sensitive data may be exposed as a result of exploitation. Availability could also be compromised, further elevating the risk profile of this vulnerability.
Risk & Impact Analysis
The real-world deployment risk associated with CVE-2021-36159 is significant. Organizations utilizing libfetch in mission-critical applications may face severe consequences if this vulnerability is exploited. The potential for unauthorized access to sensitive information raises alarms for data integrity and compliance.
The blast radius for this vulnerability could extend across multiple systems leveraging libfetch. Organizations must assess their exposure and prioritize patching within the next security cycle. Given the CVSS score of 9.1, immediate remediation is essential to safeguard against potential exploitation.
Exploitation Status
Signal | Status |
|---|---|
Known Exploit | No |
Public PoC | No |
Actively Exploited | No |
Ransomware Use | No |
Affected Versions
The vulnerability affects all versions of libfetch prior to the vendor patch released on July 26, 2021. Organizations should ensure they are running updated versions to mitigate the risk associated with CVE-2021-36159.
Mitigation & Remediation
Organizations should prioritize patching to address CVE-2021-36159. The recommended action is to update libfetch to the latest version provided by FreeBSD. If immediate patching is not feasible, organizations should implement strict network controls to limit exposure to potentially malicious traffic.
Configuration hardening should also be conducted to prevent unauthorized access to affected systems. Furthermore, continuous monitoring for any anomalous behavior related to libfetch usage is advised. For comprehensive security testing, organizations may consider engaging in penetration testing to validate the effectiveness of their remediation efforts.
Detection Guidance
Organizations should monitor logs for indicators of exploitation attempts, including unusual FTP or HTTP requests that may trigger the vulnerability. Behavioral anomalies, such as unexpected application crashes or data leaks, should be investigated promptly.
Network signatures should be established to detect potentially malicious traffic patterns, particularly targeting FTP and HTTP protocols. Furthermore, any changes to the libfetch component or related configurations should be carefully logged and reviewed.
AppSecure Threat Intelligence Insight
The long-term significance of CVE-2021-36159 lies in its demonstration of how critical vulnerabilities can emerge from overlooked input validation in widely-used libraries. This incident highlights the importance of maintaining rigorous security practices in software development, particularly in components that facilitate data transfer.
Security teams must learn from this incident to enhance their vulnerability management programs. Regularly reviewing and updating libraries and dependencies is essential to mitigate risks. Moreover, organizations should conduct thorough security assessments, including application security assessments, to identify similar weaknesses across their technology stack.
Finally, organizations should consider implementing continuous security practices, such as continuous penetration testing, to proactively identify and remediate vulnerabilities before they can be exploited.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
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