CVE-2022-48757 in Linux
Summary
by MITRE • 06/20/2024
In the Linux kernel, the following vulnerability has been resolved:
net: fix information leakage in /proc/net/ptype
In one net namespace, after creating a packet socket without binding it to a device, users in other net namespaces can observe the new `packet_type` added by this packet socket by reading `/proc/net/ptype` file. This is minor information leakage as packet socket is namespace aware.
Add a net pointer in `packet_type` to keep the net namespace of of corresponding packet socket. In `ptype_seq_show`, this net pointer must be checked when it is not NULL.
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Analysis
by VulDB Data Team • 09/17/2025
The vulnerability described in CVE-2022-48757 represents a significant information disclosure issue within the Linux kernel's networking subsystem. This flaw exists in the packet socket implementation where the /proc/net/ptype interface fails to properly enforce namespace boundaries. The vulnerability stems from the fact that packet sockets are designed to be namespace-aware entities, yet the ptype interface does not adequately verify which network namespace a packet type belongs to when displaying information to users. This creates an unintended information leakage scenario where users operating within one network namespace can access packet type information created by packet sockets in different network namespaces.
The technical implementation of this vulnerability involves the packet_type data structure which lacks proper namespace tracking mechanisms. When a packet socket is created within a specific network namespace without binding to a particular device, the associated packet_type information gets registered in a global table accessible through /proc/net/ptype. The absence of namespace validation in the ptype_seq_show function means that any user with read access to this proc file can enumerate packet types from all namespaces, effectively bypassing the intended namespace isolation. This design flaw violates fundamental security principles of process and network namespace isolation that Linux implements to maintain system security boundaries.
The operational impact of this vulnerability extends beyond simple information disclosure, as it can potentially enable attackers to gather intelligence about network configurations and packet handling mechanisms across different namespaces. While the vulnerability is classified as minor information leakage, it represents a violation of the principle of least privilege and namespace isolation that forms the foundation of Linux security architecture. An attacker could potentially use this information to better understand the network stack configuration of a target system, potentially aiding in more sophisticated attacks. The vulnerability affects systems running Linux kernels where network namespaces are utilized, particularly in containerized environments or systems with multiple isolated network domains.
The fix implemented for CVE-2022-48757 addresses the core architectural issue by adding a net pointer field to the packet_type structure. This enhancement enables the kernel to track which network namespace each packet type originates from and ensures proper validation during the ptype_seq_show operation. The solution directly addresses the root cause by implementing namespace-aware checking logic when displaying packet type information, ensuring that users can only see packet types belonging to their own network namespace or appropriately authorized namespaces. This fix aligns with security best practices outlined in the CWE-200 category for information exposure and follows the ATT&CK framework's technique T1082 for system information discovery. The mitigation approach demonstrates proper kernel security engineering by adding namespace awareness to previously unguarded interfaces, reinforcing the principle that all system interfaces must respect the security boundaries established by the kernel's namespace implementation.