CVE-2022-48620 in uev
Summary
by MITRE • 01/12/2024
uev (aka libuev) before 2.4.1 has a buffer overflow in epoll_wait if maxevents is a large number.
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Analysis
by VulDB Data Team • 01/26/2026
The vulnerability identified as CVE-2022-48620 affects the uev library also known as libuev version 2.4.1 and earlier. This library serves as a userspace event loop implementation that provides a unified interface for various event notification mechanisms including epoll, kqueue, and select. The issue manifests specifically within the epoll_wait function implementation where a buffer overflow occurs when the maxevents parameter is set to an excessively large value. This flaw represents a critical security concern as it can potentially lead to arbitrary code execution or system instability when the library processes event notifications.
The technical root cause of this vulnerability lies in improper input validation and buffer management within the epoll_wait function implementation. When a large maxevents value is passed to the function, the library fails to properly validate the input bounds before allocating or using memory buffers. This oversight creates a condition where the system attempts to write more data into a buffer than it can accommodate, leading to memory corruption that may be exploited by malicious actors. The vulnerability aligns with CWE-121, which describes stack-based buffer overflow conditions, and also relates to CWE-787, which covers out-of-bounds write vulnerabilities. The flaw operates at the kernel interface level where userspace applications interact with the epoll subsystem, making it particularly dangerous as it can be triggered through normal event loop operations.
The operational impact of this vulnerability extends beyond simple system crashes or hangs. An attacker who can control the maxevents parameter in a uev-based application could potentially execute arbitrary code with the privileges of the affected process. This represents a significant risk for applications that rely on libuev for event handling, particularly in server environments or systems handling untrusted input. The vulnerability affects systems where the library is used to implement event-driven architectures, potentially compromising the integrity of network services, daemon applications, or any software that utilizes epoll for efficient I/O multiplexing. The exploitability of this vulnerability is heightened because it requires only that an application using libuev processes a large maxevents value, which could occur through malformed input or crafted attack vectors.
Mitigation strategies for CVE-2022-48620 primarily focus on updating to the patched version of libuev 2.4.1 or later. System administrators should prioritize patching affected systems and applications that utilize this library, particularly in production environments where security is paramount. Additionally, implementing proper input validation within applications that use libuev can serve as a defensive measure, ensuring that maxevents parameters remain within reasonable bounds. The remediation approach should also include monitoring for unusual patterns in event loop operations and implementing proper bounds checking in applications that interface with the library. Organizations should consider the ATT&CK framework tactic T1059 for command and control activities, as this vulnerability could enable attackers to establish persistent access through code execution. Regular security assessments and vulnerability scanning should be conducted to identify any applications that may be indirectly affected by this issue through dependency chains. The fix implemented in version 2.4.1 addresses the core buffer management issue by introducing proper bounds checking and input validation for the maxevents parameter, ensuring that memory allocations remain within safe limits regardless of the input values provided.