Buffer Overflow in libcurl's printf() Functions
Summary
DLA-767-1: curl - security update. Affects curl versions < 7.26.0-1+wheezy18. Fixed in 7.26.0-1+wheezy18. How to fix ↓
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Background
The libcurl package is a widely used open-source library that provides client-side URL transfers. It supports various protocols, including HTTP, FTP, and SMTP, allowing applications to communicate with remote servers. This vulnerability affects the Debian 7 Wheezy version of the curl package, specifically the printf() functions within the libcurl implementation. These functions are responsible for formatting and printing output. However, due to a lack of boundary checks, a buffer overflow can occur when performing large floating point outputs, exceeding 255 bytes.
Vulnerability Detail
The buffer overflow vulnerability arises from the improper handling of floating point conversions in the printf() functions. When a conversion outputs more than 255 bytes, it triggers the buffer overflow. This flaw can be exploited by an attacker if an application accepts a format string from an external source without proper input filtering. By crafting a malicious format string, an attacker could execute arbitrary code or perform remote attacks. It is important to note that this vulnerability does not exist in the curl command line tool.
How To Fix
Minimum fixed version
7.26.0-1+wheezy18
This is the first release that contains the fix.
sudo apt-get install --only-upgrade curlTip — Not sure which version your app runs? Vulert can match this fix to it. Scan free →
Workaround
No specific workaround has been provided for this vulnerability. However, it is crucial to ensure that any application accepting format strings from external sources implements proper input filtering and validation. By validating and sanitizing user-supplied format strings, the risk of exploitation can be significantly reduced.
Conclusion
The buffer overflow vulnerability in libcurl's printf() functions can lead to remote attacks or arbitrary code execution if an application accepts unfiltered format strings. It is crucial to upgrade the curl package to version 7.26.0-1+wheezy18 or later to mitigate this risk. Implementing proper input filtering and validation for format strings can also reduce the likelihood of exploitation. For further support on vulnerability remediation, please contact DevNack.com.
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FAQ
libcurl is an open-source library that enables client-side URL transfers, supporting various protocols like HTTP, FTP, and SMTP. It allows applications to communicate with remote servers.
This vulnerability affects Debian 7 Wheezy.
If exploited, this vulnerability can allow remote attacks or arbitrary code execution. It is crucial to upgrade the curl package to mitigate the risk.
No, this vulnerability does not exist in the curl command line tool.
You can find further information about Debian LTS security advisories, including how to apply updates and frequently asked questions, on the Debian LTS wiki.
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