Critical Vulnerability in curl: Authority Component Parsing Flaw
Summary
ALPINE-CVE-2016-8624: curl before version 7.51.0 doesn't parse the authority component of the URL correctly when the host name part ends with a '#' character, and could instead be tricked into connecting to a different host. 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 often integrated into applications for data retrieval and file transfers. However, certain versions of curl prior to 7.51.0 are vulnerable to a flaw that affects how it parses URLs, particularly when the hostname ends with a '#' character.
Vulnerability Detail
The vulnerability arises from curl's improper handling of the authority component in URLs. Specifically, when a hostname ends with a '#', curl may be misled into connecting to an unintended host. This misbehavior can lead to security implications, especially if curl is used in conjunction with URL parsers that validate domains according to RFC standards. Attackers could exploit this flaw to redirect requests to malicious servers, potentially compromising sensitive data.
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
If updating is not immediately feasible, consider using an alternative method for URL parsing that does not rely on curl's authority component handling. Additionally, avoid using URLs that end with a '#' character until the vulnerability is addressed.
Conclusion
The vulnerability in curl regarding the parsing of the authority component poses significant security risks. Users are strongly advised to update to the latest patched versions to mitigate these risks. For those unable to update immediately, workarounds are available to reduce exposure.
See every vulnerability recorded for curl →
FAQ
All versions of curl prior to 7.51.0 are affected by this vulnerability.
The primary risk is that an attacker could redirect requests to a malicious server, leading to data breaches or unauthorized access.
You can use Vulert's playground at Vulert Scanner to check if your application is affected by this vulnerability without needing to sign up.
Yes, avoid using URLs that end with a '#' character and consider alternative URL parsing methods.
The CVSS score for this vulnerability is 7.5, indicating a high severity level.
References
Related vulnerabilities
Recent vulnerabilities recorded for curl.
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