CVE-2022-2905 in Linux
Summary
by MITRE • 09/09/2022
An out-of-bounds memory read flaw was found in the Linux kernel's BPF subsystem in how a user calls the bpf_tail_call function with a key larger than the max_entries of the map. This flaw allows a local user to gain unauthorized access to data.
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Analysis
by VulDB Data Team • 05/28/2026
The vulnerability identified as CVE-2022-2905 represents a critical out-of-bounds memory read issue within the Linux kernel's Berkeley Packet Filter (BPF) subsystem. This flaw resides in the bpf_tail_call function implementation where improper validation occurs when processing user-supplied keys that exceed the maximum entries allowed within a BPF map structure. The BPF subsystem serves as a powerful kernel feature enabling userspace programs to execute sandboxed bytecode directly within the kernel, making it a critical component for network filtering, tracing, and system monitoring operations. When a malicious user invokes bpf_tail_call with an oversized key parameter, the kernel fails to properly bounds-check the input against the map's configured maximum entries, leading to memory access violations that can expose sensitive kernel data to unauthorized access.
The technical nature of this vulnerability stems from inadequate input validation within the BPF map lookup mechanism. Specifically, when the bpf_tail_call function processes a key value that surpasses the max_entries limit configured for the target BPF map, the kernel's memory access routines do not properly sanitize this input before proceeding with memory operations. This creates a scenario where the kernel attempts to read memory locations beyond the allocated map boundaries, potentially exposing kernel memory contents including sensitive data structures, cryptographic keys, or other confidential information. The vulnerability manifests as a local privilege escalation vector since any user with access to the BPF subsystem can trigger this condition, though it requires the user to have the necessary permissions to interact with BPF functionality and access the specific map structures in question.
From an operational impact perspective, this vulnerability compromises the fundamental security model of the Linux kernel by enabling unauthorized data access through a well-established kernel subsystem. The flaw affects systems running Linux kernel versions where the BPF subsystem is enabled and accessible to userspace applications. Attackers can leverage this vulnerability to extract sensitive kernel memory contents, potentially including credentials, cryptographic material, or system configuration details that could be used for further exploitation or lateral movement within the compromised system. The local nature of the vulnerability means that exploitation does not require network access or remote attack vectors, making it particularly dangerous in environments where users have access to BPF functionality or where containers or virtual machines share host kernel resources.
Mitigation strategies for CVE-2022-2905 primarily involve applying the official kernel patches released by the Linux kernel security team, which address the bounds-checking issue in the BPF subsystem's bpf_tail_call implementation. System administrators should prioritize updating their kernel versions to include the fixes provided by the kernel maintainers, particularly focusing on versions that contain the necessary security patches. Additionally, organizations should implement monitoring and logging of BPF-related system calls to detect potential exploitation attempts, as the vulnerability requires specific BPF map access patterns to be triggered. The mitigation approach aligns with the principle of least privilege, ensuring that users with access to BPF functionality have appropriate restrictions and that unnecessary BPF capabilities are disabled in production environments. This vulnerability is classified under CWE-129 as an Improper Validation of Array Index, and the attack pattern relates to privilege escalation techniques documented in the MITRE ATT&CK framework under T1068 for Local Privilege Escalation.