CVE-2016-9586 in macOS
Summary
by MITRE
curl before version 7.52.0 is vulnerable to a buffer overflow when doing a large floating point output in libcurl's implementation of the printf() functions. If there are any application that accepts a format string from the outside without necessary input filtering, it could allow remote attacks.
If you want to get best quality of vulnerability data, you may have to visit VulDB.
Analysis
by VulDB Data Team • 12/13/2022
The vulnerability identified as CVE-2016-9586 represents a critical buffer overflow flaw within curl's libcurl library implementation of printf() functions. This issue affects curl versions prior to 7.52.0 and stems from improper handling of large floating point number formatting operations. The flaw occurs when the library processes format strings containing floating point values that exceed normal buffer boundaries, creating conditions where memory corruption can occur. The vulnerability specifically manifests during the internal processing of printf-style formatting operations where the library fails to properly validate or limit the output buffer size when dealing with large floating point numbers.
The technical exploitation of this vulnerability requires an attacker to influence the format string used in curl's printf implementation through external input sources. When applications fail to properly filter or sanitize format string parameters before passing them to curl functions, malicious actors can craft specially formatted input that triggers the buffer overflow condition. This creates potential for arbitrary code execution or denial of service attacks, as the overflow can overwrite adjacent memory regions including return addresses and control data. The vulnerability aligns with CWE-121, which describes buffer overflow conditions where insufficient space is allocated for data, and falls under the broader category of CWE-787, representing out-of-bounds write vulnerabilities.
The operational impact of CVE-2016-9586 extends beyond simple application crashes, as it can enable sophisticated attack vectors that leverage the buffer overflow for privilege escalation or system compromise. Attackers can exploit this vulnerability in web applications, network services, or any software that relies on curl for HTTP operations and accepts user-provided format strings. The risk is particularly elevated in environments where curl is used as a library component in larger applications without proper input validation. This vulnerability can be classified under ATT&CK technique T1203, which involves exploitation of input validation weaknesses, and represents a common entry point for attackers seeking to establish persistent access or execute malicious code within target systems.
Mitigation strategies for CVE-2016-9586 require immediate patching of curl installations to version 7.52.0 or later, where the buffer overflow has been resolved through proper bounds checking and memory allocation. Organizations should implement comprehensive input validation procedures that sanitize all external format string inputs before processing them through curl functions. Additionally, application developers should adopt defensive programming practices such as using secure printf alternatives that automatically handle buffer sizing, implementing proper error handling for floating point formatting operations, and conducting regular security assessments of third-party libraries. Network segmentation and intrusion detection systems can provide additional layers of protection by monitoring for suspicious format string patterns that may indicate exploitation attempts. The vulnerability serves as a reminder of the critical importance of maintaining up-to-date software libraries and implementing robust input validation controls to prevent exploitation of fundamental security flaws in widely-used components.