CVE-2023-4813 in C Library
Summary
by MITRE • 09/13/2023
A flaw was found in glibc. In an uncommon situation, the gaih_inet function may use memory that has been freed, resulting in an application crash. This issue is only exploitable when the getaddrinfo function is called and the hosts database in /etc/nsswitch.conf is configured with SUCCESS=continue or SUCCESS=merge.
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Analysis
by VulDB Data Team • 05/17/2025
The vulnerability identified as CVE-2023-4813 represents a critical memory safety issue within the GNU C Library glibc that manifests through improper memory management during network address resolution operations. This flaw specifically affects the gaih_inet function which handles internet address resolution, creating a scenario where freed memory locations are accessed, leading to potential application instability and system crashes. The vulnerability operates within a narrow but significant operational context that requires specific configuration conditions to be exploitable, making it particularly insidious as it may not be immediately apparent during normal system operation.
The technical root cause of this vulnerability stems from improper memory deallocation and subsequent usage patterns within the gaih_inet function implementation. When the getaddrinfo function processes network resolution requests, it relies on the Name Service Switch mechanism configured in /etc/nsswitch.conf to determine how to handle different name resolution sources. The vulnerability becomes exploitable specifically when the hosts database configuration uses SUCCESS=continue or SUCCESS=merge directives, which create a particular execution flow where memory allocated for address resolution is freed but subsequently accessed. This memory access violation occurs through a classic use-after-free vulnerability pattern that falls under CWE-416, representing improper deallocation of memory resources.
The operational impact of CVE-2023-4813 extends beyond simple application crashes to potentially compromise system stability and availability, particularly in environments where network services are heavily utilized. Applications that frequently call getaddrinfo for hostname resolution, including web servers, database systems, and network daemons, become vulnerable to this memory corruption issue. The vulnerability's exploitation requires specific conditions that make it less likely to be triggered accidentally, but when it does occur, it can lead to denial of service scenarios that affect legitimate user access to network services. This issue aligns with ATT&CK technique T1499.004 for network denial of service attacks, as it can be leveraged to disrupt network service availability through controlled memory corruption.
Mitigation strategies for CVE-2023-4813 must address both the immediate system vulnerabilities and the underlying configuration issues that enable exploitation. System administrators should prioritize updating to patched versions of glibc where available, as this represents the most direct and effective remediation approach. Additionally, reviewing and modifying the /etc/nsswitch.conf configuration to avoid using SUCCESS=continue or SUCCESS=merge directives for hosts database entries can significantly reduce the attack surface. Organizations should also implement monitoring solutions to detect unusual application crashes or memory access patterns that may indicate exploitation attempts. The vulnerability's characteristics make it particularly relevant to security frameworks that emphasize memory safety and proper resource management practices, as highlighted in industry standards that focus on preventing use-after-free conditions and maintaining proper memory lifecycle management.