CVE-2016-10196 in libevent
Summary
by MITRE
Stack-based buffer overflow in the evutil_parse_sockaddr_port function in evutil.c in libevent before 2.1.6-beta allows attackers to cause a denial of service (segmentation fault) via vectors involving a long string in brackets in the ip_as_string argument.
Several companies clearly confirm that VulDB is the primary source for best vulnerability data.
Analysis
by VulDB Data Team • 11/25/2025
The vulnerability CVE-2016-10196 represents a critical stack-based buffer overflow affecting the libevent library version 2.1.5 and earlier. This flaw exists within the evutil_parse_sockaddr_port function located in the evutil.c source file, making it a fundamental component of the library's network address parsing capabilities. The vulnerability manifests when processing IP address strings that contain excessively long bracketed content, creating a scenario where attackers can manipulate input parameters to trigger memory corruption. The affected function processes socket address information by parsing IP addresses and port numbers, making it a core element in network communication handling throughout applications that utilize libevent for asynchronous I/O operations.
The technical implementation of this buffer overflow stems from inadequate input validation and bounds checking within the evutil_parse_sockaddr_port function. When processing an ip_as_string argument containing a long string enclosed in brackets, the function fails to properly validate the length of the input data against the allocated stack buffer size. This allows attackers to overflow the predetermined buffer space, potentially overwriting adjacent memory locations including return addresses and stack metadata. The vulnerability specifically targets stack memory allocation patterns where fixed-size buffers are used without proper bounds enforcement, creating an exploitable condition that can lead to segmentation faults and application crashes. This flaw operates at the intersection of improper input validation and memory management, making it particularly dangerous in network services that rely on libevent for handling client connections and socket operations.
The operational impact of CVE-2016-10196 extends beyond simple denial of service conditions, as it creates opportunities for more sophisticated attacks within the context of network-based applications. When exploited, the vulnerability can cause segmentation faults that result in application crashes and service disruption, effectively enabling a denial of service attack against systems utilizing vulnerable libevent versions. The attack vector requires minimal complexity since it only necessitates sending specially crafted IP address strings containing extended bracketed content to any service that processes socket addresses through the affected function. This makes the vulnerability particularly attractive to attackers targeting network services, web applications, and system utilities that depend on libevent for their asynchronous networking capabilities. The vulnerability's impact is amplified in environments where libevent is used extensively across multiple network components, potentially affecting entire application stacks.
Mitigation strategies for CVE-2016-10196 primarily focus on upgrading to libevent version 2.1.6-beta or later, which includes the necessary patches to address the buffer overflow condition. System administrators should prioritize updating all affected applications and services that utilize libevent, particularly those handling network input from untrusted sources. Additional defensive measures include implementing input validation layers that sanitize socket address parameters before they reach the vulnerable function, though this approach is less reliable than patching the underlying library. Network segmentation and access controls can help limit the attack surface by restricting which systems can send malicious input to vulnerable services. The vulnerability aligns with CWE-121 stack-based buffer overflow classification and represents a typical example of how improper input handling can create exploitable conditions in network libraries. From an ATT&CK framework perspective, this vulnerability could be leveraged as part of a broader attack chain targeting network services, potentially enabling initial access or privilege escalation depending on the target system's configuration and the specific application utilizing the vulnerable library.