Client Certificate Validation Flaw in curl: CVE-2016-5420
Summary
ALPINE-CVE-2016-5420: curl and libcurl before 7.50.1 do not check the client certificate when choosing the TLS connection to reuse, which might allow remote attackers to hijack the authentication of the connection by leveraging a previously c... Affects curl versions < 7.50.1-r0. Fixed in 7.50.1-r0. How to fix ↓
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Background
curl is a widely used command-line tool and library for transferring data with URLs. It supports various protocols including HTTP, HTTPS, FTP, and more. curl is known for its versatility and ease of use, making it a staple in web development and network operations. However, prior to version 7.50.1, curl had a significant vulnerability that affected its handling of client certificates during TLS connections.
Vulnerability Detail
The vulnerability, identified as CVE-2016-5420, arises from curl and libcurl's failure to properly check the client certificate when reusing TLS connections. This oversight allows remote attackers to hijack the authentication of a connection by exploiting a previously established connection that utilized a different client certificate. The implications of this vulnerability are severe, as it could lead to unauthorized access and data breaches, particularly in environments where secure connections are critical.
How To Fix
Minimum fixed version
7.50.1-r0
This is the first release that contains the fix.
sudo apk add --upgrade curlTip — Not sure which version your app runs? Vulert can match this fix to it. Scan free →
Workaround
As a temporary workaround, users can avoid reusing TLS connections or ensure that client certificates are consistently validated across connections. However, this is not a permanent solution and updating to the patched version is strongly recommended.
Conclusion
CVE-2016-5420 represents a significant security risk for users of curl and libcurl prior to version 7.50.1. It is crucial for users to update their installations to the patched version to protect against potential attacks that exploit this vulnerability. Utilizing tools like Vulert can help in monitoring and identifying vulnerabilities in open-source software.
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FAQ
CVE-2016-5420 is a vulnerability in curl and libcurl that allows attackers to hijack TLS connections by exploiting improper client certificate validation.
You can use Vulert, which monitors open-source vulnerabilities in real-time. By uploading your manifest file like package-lock.json, you can check for vulnerabilities without any installation.
The vulnerability can lead to unauthorized access and potential data breaches, especially in secure environments relying on TLS connections.
Yes, the vulnerability is patched in curl version 7.50.1 and later. Users should update to this version to mitigate the risk.
The CVSS score for CVE-2016-5420 is 7.5, indicating a high severity level.
References
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