CVE-2019-17054 in Linux
Summary
by MITRE
atalk_create in net/appletalk/ddp.c in the AF_APPLETALK network module in the Linux kernel through 5.3.2 does not enforce CAP_NET_RAW, which means that unprivileged users can create a raw socket, aka CID-6cc03e8aa36c.
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Analysis
by VulDB Data Team • 08/10/2025
The vulnerability identified as CVE-2019-17054 resides within the Linux kernel's AppleTalk network implementation, specifically in the atalk_create function located in net/appletalk/ddp.c. This flaw represents a significant privilege escalation issue that undermines the kernel's security model by allowing unprivileged users to bypass critical access controls. The AppleTalk protocol implementation is designed to handle network communications for AppleTalk networks, which historically provided networking capabilities for early apple computer systems. However, the vulnerability manifests in the kernel's failure to properly validate user privileges when creating raw sockets, creating an avenue for unauthorized access to network resources that should be restricted to privileged processes.
The technical flaw stems from the atalk_create function's insufficient enforcement of the CAP_NET_RAW capability check. In Linux security architecture, CAP_NET_RAW is a critical capability that grants processes the ability to create raw network sockets, which can be used to craft and send arbitrary network packets. When this capability is not properly enforced, it allows users without elevated privileges to create raw sockets that can potentially be used for malicious network activities. This represents a direct violation of the principle of least privilege that forms the foundation of Linux security model. The vulnerability is particularly concerning because raw socket creation can enable users to perform packet sniffing, network reconnaissance, and potentially craft malicious network traffic that could compromise network security.
The operational impact of this vulnerability extends beyond simple privilege escalation, as it provides attackers with capabilities that can be leveraged for broader network infiltration. Unprivileged users who exploit this vulnerability can create raw sockets that may be used for network scanning, packet injection, and other malicious activities that would normally require root privileges or specific network administration capabilities. This vulnerability aligns with CWE-276, which describes improper privilege management, and represents a clear violation of the security principle that network socket creation should be restricted to processes with appropriate authorization. The implications are particularly severe in multi-user environments where untrusted users might gain access to systems and leverage this vulnerability to compromise network integrity and confidentiality.
Mitigation strategies for CVE-2019-17054 focus on both immediate patching and system hardening approaches. The most effective solution involves applying the kernel patch that was released to address the specific capability enforcement issue in the atalk_create function. This patch ensures that the CAP_NET_RAW capability is properly validated before allowing raw socket creation. Additionally, system administrators should consider implementing mandatory access controls through SELinux or AppArmor policies that further restrict network socket creation capabilities. Network segmentation and monitoring should be enhanced to detect anomalous network traffic patterns that might indicate exploitation attempts. From an ATT&CK framework perspective, this vulnerability maps to T1068, which covers the use of privilege escalation techniques, and T1046, which involves network service scanning. The vulnerability also demonstrates the importance of maintaining up-to-date kernel versions and implementing comprehensive security monitoring to detect and prevent exploitation of kernel-level vulnerabilities that can provide attackers with elevated system access.