Critical Vulnerability in Curl Package: Buffer Overflow Risk Due to Improper URL Decoding
Summary
ALPINE-CVE-2016-8622: The URL percent-encoding decode function in libcurl before 7.51.0 is called curl_easy_unescape. Affects curl versions < 7.51.0-r0. Fixed in 7.51.0-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 is commonly integrated into applications for network communication. However, it has a vulnerability related to its URL percent-encoding decode function, which can lead to severe security risks if not addressed.
Vulnerability Detail
The vulnerability, identified as CVE-2016-8622, arises from the curl_easy_unescape function in libcurl versions prior to 7.51.0. This function is responsible for decoding percent-encoded URLs. The issue occurs when the function allocates a destination buffer larger than 2GB, as it returns the new length in a signed 32-bit integer. Consequently, the length may be truncated or turned negative, leading to potential heap-based buffer overflows. This vulnerability can allow attackers to execute arbitrary code, leading to system compromise.
How To Fix
Minimum fixed version
7.51.0-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, avoid using the curl_easy_unescape function with inputs that could exceed the 2GB limit. Additionally, consider implementing input validation to ensure that URLs processed by Curl do not exceed safe length limits.
Conclusion
The vulnerability CVE-2016-8622 in the Curl package poses significant risks due to improper URL decoding, potentially leading to buffer overflows. It is crucial for users to update to the patched version 7.51.0 or later to mitigate these risks. Additionally, utilizing tools like Vulert can help in monitoring and managing vulnerabilities in open-source software.
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FAQ
CVE-2016-8622 is a vulnerability in the Curl package that can lead to buffer overflow due to improper handling of URL decoding.
You can use the Vulert playground at Vulert Scanner to check if your application is affected by this vulnerability without needing to sign up.
The risks include potential arbitrary code execution, which can lead to system compromise and unauthorized access to sensitive data.
You can update Curl by using the command apk add curl@7.51.0 for Alpine Linux users, or the equivalent command for your package manager.
Yes, Vulert provides a service that monitors and alerts for open-source vulnerabilities in your software using just a manifest file like package-lock.json.
References
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