CVE-2016-5421 in macOS
Summary
by MITRE
Use-after-free vulnerability in libcurl before 7.50.1 allows attackers to control which connection is used or possibly have unspecified other impact via unknown vectors.
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Analysis
by VulDB Data Team • 10/07/2022
The CVE-2016-5421 vulnerability represents a critical use-after-free flaw within the libcurl library version 7.50.0 and earlier, which serves as a fundamental component for HTTP and HTTPS communication in countless applications and systems. This vulnerability arises from improper memory management practices where freed memory blocks are still referenced or accessed by subsequent operations, creating potential attack vectors that could be exploited by malicious actors. The affected library is widely deployed across operating systems, web browsers, email clients, and various networked applications, making the impact of this flaw pervasive throughout the cybersecurity landscape.
The technical implementation of this use-after-free vulnerability occurs within libcurl's connection handling mechanisms, specifically when managing multiple concurrent connections or when transitioning between different connection states. Attackers can manipulate the library's behavior through carefully crafted inputs that cause the application to free memory associated with a connection handle while other parts of the codebase might still reference that memory location. This memory corruption can lead to arbitrary code execution, denial of service conditions, or potentially enable privilege escalation depending on the target system's security context. The vulnerability's exploitation requires precise timing and understanding of the library's internal state management, making it particularly dangerous as it can be leveraged across different attack vectors and environments.
The operational impact of CVE-2016-5421 extends far beyond individual application failures, as libcurl is embedded within numerous software products and operating system components. This includes web browsers like Chrome and Firefox, email clients, content management systems, and enterprise applications that rely on secure network communication. When exploited, the vulnerability could allow attackers to execute arbitrary code with the privileges of the affected application, potentially leading to complete system compromise. The unspecified other impacts mentioned in the description suggest that the flaw could enable additional attack vectors beyond direct code execution, including information disclosure or privilege escalation scenarios that could be particularly devastating in enterprise environments.
Mitigation strategies for this vulnerability primarily focus on immediate remediation through library updates to version 7.50.1 or later, which contain the necessary memory management fixes. System administrators should prioritize patching all affected applications and operating systems that utilize vulnerable versions of libcurl, particularly in production environments where the risk of exploitation is highest. Additionally, implementing network segmentation and monitoring for unusual connection patterns or memory access violations can help detect potential exploitation attempts. Security teams should also consider deploying intrusion detection systems that can identify suspicious network behavior patterns associated with known exploitation techniques. The vulnerability aligns with CWE-416, which specifically addresses use-after-free conditions, and represents a significant concern for organizations following ATT&CK framework's privilege escalation and code execution tactics. Organizations should conduct comprehensive vulnerability assessments to identify all systems using vulnerable versions of libcurl and establish monitoring procedures to detect potential exploitation attempts.