CVE-2021-22946 is a high-severity vulnerability affecting curl versions 7.20.0 to 7.78.0. This vulnerability allows a user to instruct curl to require a successful upgrade to TLS when communicating with IMAP, POP3, or FTP servers. However, this requirement can be bypassed if the server responds with a legitimate but crafted response, causing curl to operate without TLS, thereby exposing sensitive data in clear text over the network.
The vulnerability has been assigned a CVSS score of 7.5, indicating a high level of risk. This rating reflects the potential for significant confidentiality impact, as sensitive data could be intercepted during transmission. Organizations utilizing affected versions of curl should take immediate action to mitigate this vulnerability.
Given the risk to organizations includes unauthorized access to sensitive data, it is critical that users of affected curl versions prioritize remediation efforts. The urgency for defenders is high, and organizations should address this vulnerability in their patch cycles.
As of now, there are no known exploits in the wild, but the vulnerability's nature and the absence of a public proof-of-concept (PoC) means that security teams should be vigilant in monitoring their systems for any signs of exploitation.
Organizations should remain proactive in their security posture by regularly updating their software and conducting vulnerability assessments to identify potential weaknesses.
Vulnerability Details
The CVE-2021-22946 vulnerability occurs in curl versions ranging from 7.20.0 to 7.78.0, where users can specify a requirement for TLS upgrades when interfacing with certain servers. If the server responds in a specific manner, it can lead to curl continuing operations without the expected TLS protection, thus exposing potentially sensitive data.
This vulnerability has been classified under CWE-319 (Cleartext Transmission of Sensitive Information) and CWE-325 (Insufficiently Protected Credentials). The CVSS score of 7.5 indicates a high severity, primarily due to the confidentiality impact being rated as high.
Technical Analysis
The root cause of this vulnerability lies in the handling of TLS requirements in curl. When a user specifies the need for TLS, the expectation is that all communications should be encrypted. However, if a server returns a crafted response, curl may ignore the TLS requirement and proceed with unsecured communication.
The attack vector is network-based, where an attacker could intercept communications between curl and the server. Given the low attack complexity and the requirement for no privileges, this vulnerability can be exploited without requiring any special access or user interaction.
The implications of this vulnerability extend to confidentiality, as sensitive data transmitted could be exposed in plaintext. Integrity and availability impacts are not applicable in this context.
Risk & Impact Analysis
Organizations deploying curl in any capacity must consider the potential risks associated with this vulnerability. The possibility of sensitive data being transmitted without encryption poses a significant threat, especially for organizations handling personal or financial information.
With the increasing reliance on secure communications, the exploitation of this vulnerability could have wide-reaching consequences, including regulatory non-compliance and damage to an organization's reputation.
Given that the CVSS score indicates high severity, organizations should prioritize remediation efforts. Regular monitoring for any potential exploitation attempts should be part of a comprehensive security strategy.
Exploitation Status
Signal | Status |
|---|---|
Known Exploit | No |
Public PoC | No |
Actively Exploited | No |
Ransomware Use | No |
Affected Versions
The following versions of curl are affected by this vulnerability: all versions between 7.20.0 and 7.78.0. Additionally, various products and components utilizing curl, such as Debian Linux (versions 9.0, 10.0, and 11.0), Fedora (versions 33 and 35), and several NetApp products, are also vulnerable.
Mitigation & Remediation
To mitigate the risk associated with CVE-2021-22946, it is critical that organizations apply the latest patches for curl. Users should upgrade to a version beyond 7.78.0 to ensure protection against this vulnerability. If patches are unavailable, organizations should consider limiting the use of curl for sensitive operations and implement stringent network controls to monitor unencrypted traffic.
Continuous penetration testing can be beneficial to validate the effectiveness of remediation efforts and to identify potential weaknesses in the system.
Detection Guidance
Organizations should monitor logs for unusual responses from servers that curl interacts with, particularly those that might indicate a TLS downgrade. Additionally, network signatures should be established to detect any unencrypted traffic that is expected to be secure.
AppSecure Threat Intelligence Insight
CVE-2021-22946 represents a significant pattern in vulnerabilities where the expectation of secure communications is undermined. Such vulnerabilities highlight the need for organizations to enforce strict security measures and ensure that all data transmissions are adequately protected. This incident reinforces the importance of regular security assessments and the need for organizations to stay informed about potential vulnerabilities in their software stack.
Organizations are encouraged to regularly review their security documentation and implement comprehensive security training for their teams. In addition, adopting a proactive approach to security through regular vulnerability assessments and timely patching can significantly reduce the risk of exploitation.
For further reading on vulnerability management, organizations can refer to our vulnerability management program guide.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
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