CVE-2021-22926 is a high-severity vulnerability that allows libcurl-using applications to improperly handle client certificates during TLS connections. This vulnerability arises when an application requests a specific client certificate using the `CURLOPT_SSLCERT` option while built with the macOS native TLS library Secure Transport. If the application runs in a directory writable by other users, a malicious actor can create a file with the same name as the intended certificate, tricking the application into using the wrong certificate. This can lead to unauthorized access, as the incorrect client certificate may be sent during the TLS handshake.
The CVSS score for this vulnerability is 7.5, classified as high severity, indicating a significant risk to organizations. The attack vector is network-based with low complexity and no privileges required, making it easier for attackers to exploit. Organizations should prioritize patching immediately to mitigate this risk.
Currently, this vulnerability does not appear to have any known exploits or public proof of concept available. However, the potential for exploitation remains a concern, particularly for systems running affected versions of libcurl and other associated products.
Organizations should ensure that their systems are not running affected versions of libcurl and should apply any available patches or updates as part of their security maintenance protocols.
Vulnerability Details
The vulnerability is categorized under CWE-295, which refers to improper certificate validation. The affected software includes Haxx Curl, several NetApp products, and Oracle MySQL Server. The vulnerability was published on August 5, 2021, with a CVSS version of 3.1.
Technical Analysis
The root cause of this vulnerability lies in how libcurl handles client certificates. When an application requests a certificate by name, it can inadvertently accept a file-based certificate if the current working directory is writable by other users. This can lead to a situation where an attacker creates a malicious file that the application uses instead of the intended certificate, compromising the integrity of the TLS handshake.
The attack vector is network-based with low complexity, requiring no privileges or user interaction. The confidentiality impact is none, but the availability impact is high, as the incorrect certificate could lead to denial of service or unauthorized access.
Risk & Impact Analysis
Risk to organizations includes the potential for unauthorized access and data leakage if the wrong client certificate is sent during TLS handshakes. This vulnerability could be exploited in environments where libcurl is deployed, particularly affecting applications that rely on secure communications.
Due to its high CVSS score and the implications of improper certificate handling, organizations should address this vulnerability in their priority patch cycle. The potential for exploitation in environments with writable directories increases the urgency for remediation.
Exploitation Status
Signal | Status |
|---|---|
Known Exploit | No |
Public PoC | No |
Actively Exploited | No |
Ransomware Use | No |
Affected Versions
The following versions are affected by CVE-2021-22926: Haxx Curl versions from 7.33.0 to 7.78.0 (exclusive), NetApp Active IQ Unified Manager, Oracle MySQL Server versions 5.7.0 to 5.7.35 and 8.0.0 to 8.0.26, and various other NetApp and Oracle products. If version information is missing, organizations should consider all versions prior to vendor patch.
Mitigation & Remediation
To remediate this vulnerability, organizations should apply patches or updates provided by the respective vendors. For Haxx Curl, ensure that you are using a version later than 7.78.0. Additionally, organizations should restrict permissions on directories that may be writable by untrusted users, such as `/tmp`, to prevent the creation of malicious files that can exploit this vulnerability.
For comprehensive security, consider implementing penetration testing to identify similar weaknesses in your applications.
Detection Guidance
Organizations should monitor logs for any anomalies related to client certificate usage. Behavioral indicators such as unexpected certificate requests or the use of certificates from untrusted directories should be flagged and investigated. Implementing network signatures to detect unusual certificate activities can also enhance detection capabilities.
AppSecure Threat Intelligence Insight
The long-term significance of CVE-2021-22926 highlights the importance of secure certificate handling in applications. As organizations increasingly rely on secure communications, vulnerabilities like this can lead to severe consequences if left unaddressed. It is crucial for security teams to regularly assess their applications for such weaknesses and ensure that proper security practices are in place.
This vulnerability represents a trend toward exploitation of improper certificate validation, which can be leveraged by attackers in various environments. Security teams should learn from this incident to bolster their defenses against similar vulnerabilities in the future.
Organizations are encouraged to develop a robust incident response plan that includes mitigation strategies for vulnerabilities like CVE-2021-22926. Regular training sessions and awareness programs can help prepare teams to respond effectively to such threats.
For further reading on improving application security, consider the following resources: Application Security Assessment, Penetration Testing Methodology, and Vulnerability Management Program Design.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
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