CVE-2022-1055 in Linux
Summary
by MITRE • 03/29/2022
A use-after-free exists in the Linux Kernel in tc_new_tfilter that could allow a local attacker to gain privilege escalation. The exploit requires unprivileged user namespaces. We recommend upgrading past commit 04c2a47ffb13c29778e2a14e414ad4cb5a5db4b5
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Analysis
by VulDB Data Team • 05/18/2025
The vulnerability identified as CVE-2022-1055 represents a critical use-after-free condition within the Linux kernel's traffic control subsystem, specifically affecting the tc_new_tfilter function. This flaw exists in the kernel's implementation of traffic control filters, which are essential components for managing network packet filtering and classification. The vulnerability manifests when processing traffic control operations through the netlink interface, where improper memory management leads to a situation where freed memory locations are accessed after they have been deallocated. The flaw is particularly concerning because it operates within kernel space, providing a direct pathway for privilege escalation attacks.
The technical execution of this vulnerability requires an attacker to possess unprivileged user namespaces, which are readily available in modern Linux systems where user namespace support is enabled. The exploit leverages the use-after-free condition to corrupt kernel memory structures, potentially allowing arbitrary code execution with kernel privileges. This attack vector aligns with the CWE-416 vulnerability classification, which specifically addresses use-after-free errors that occur when memory is freed but subsequently accessed. The attack chain begins with a user namespace creation, followed by careful manipulation of traffic control filter operations that trigger the memory corruption, ultimately leading to privilege escalation from user-level to kernel-level execution.
The operational impact of this vulnerability extends beyond simple privilege escalation, as it fundamentally undermines the security boundaries that separate user processes from kernel space. Attackers can leverage this flaw to execute malicious code with the highest system privileges, potentially gaining complete control over affected systems. This vulnerability affects all Linux kernel versions where the problematic code path remains unpatched, making it particularly dangerous in environments where kernel updates are delayed or restricted. The exploitability of this vulnerability is further enhanced by the fact that it does not require special privileges beyond what is normally available to unprivileged users, making it accessible to a wide range of potential attackers.
The recommended mitigation strategy involves upgrading the Linux kernel to a version that includes the fix committed at 04c2a47ffb13c29778e2a14e414ad4cb5a5db4b5. This specific commit addresses the memory management issue by ensuring proper reference counting and validation of traffic control filter operations before memory deallocation occurs. Organizations should also consider implementing additional security controls such as restricting user namespace creation where possible, monitoring for unusual traffic control operations, and maintaining up-to-date kernel security patches. The vulnerability demonstrates the importance of proper memory management in kernel space operations and highlights the critical nature of maintaining current security patches to protect against sophisticated privilege escalation attacks that target core system components.