CVE-2023-52880 in Linux
Summary
by MITRE • 05/24/2024
In the Linux kernel, the following vulnerability has been resolved:
tty: n_gsm: require CAP_NET_ADMIN to attach N_GSM0710 ldisc
Any unprivileged user can attach N_GSM0710 ldisc, but it requires CAP_NET_ADMIN to create a GSM network anyway.
Require initial namespace CAP_NET_ADMIN to do that.
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Analysis
by VulDB Data Team • 12/17/2025
The vulnerability identified as CVE-2023-52880 resides within the Linux kernel's terminal line discipline subsystem, specifically affecting the n_gsm driver implementation. This issue represents a privilege escalation concern that undermines the kernel's security model by allowing unprivileged users to attach the N_GSM0710 line discipline without proper authorization. The n_gsm driver is designed to handle GSM 07.10 protocol communications, typically used for modem communication and serial data transmission over GSM networks. The flaw occurs in the kernel's tty subsystem where line disciplines manage the transformation of data between user space applications and kernel drivers.
The technical implementation flaw stems from insufficient privilege checking during the line discipline attachment process. When an unprivileged user attempts to attach the N_GSM0710 line discipline, the kernel previously allowed this operation without requiring elevated privileges. However, the actual creation and configuration of GSM network connections within this framework necessitates the CAP_NET_ADMIN capability, which controls network administration operations. This discrepancy creates a security gap where users can establish the line discipline framework but cannot complete the network setup process, yet the vulnerability allows bypassing this restriction entirely.
The operational impact of this vulnerability extends beyond simple privilege escalation, as it enables potential attackers to manipulate network communication channels through the GSM line discipline interface. An unprivileged user could theoretically establish a communication channel that would later allow for network packet interception, manipulation, or even unauthorized network access depending on the system configuration. This vulnerability affects systems that utilize GSM modems or serial communication interfaces where the N_GSM0710 line discipline is enabled and accessible to regular users. The attack vector is particularly concerning in environments where physical access to terminals or where users have shell access to systems running affected kernels.
The remediation for CVE-2023-52880 requires kernel-level changes that enforce proper capability checks during the line discipline attachment process. This fix ensures that any user attempting to attach the N_GSM0710 line discipline must possess the CAP_NET_ADMIN capability from the outset, aligning the privilege requirements with the actual network administration capabilities that the functionality requires. The solution follows established security principles from the Common Weakness Enumeration framework, specifically addressing CWE-276 which deals with improper privilege management. This vulnerability also relates to ATT&CK technique T1068 which involves local privilege escalation through kernel vulnerabilities, and T1566 which covers social engineering tactics involving system access manipulation. The fix represents a defensive programming approach that ensures capability checks occur at the appropriate time during system operation, preventing unauthorized access to network administration functions through indirect pathways. This remediation aligns with the principle of least privilege enforcement and helps maintain the integrity of the Linux kernel's security model by ensuring that network administration capabilities remain restricted to appropriately authorized users.