CVE-2026-23084 in Linux
Summary
by MITRE • 02/04/2026
In the Linux kernel, the following vulnerability has been resolved:
be2net: Fix NULL pointer dereference in be_cmd_get_mac_from_list
When the parameter pmac_id_valid argument of be_cmd_get_mac_from_list() is set to false, the driver may request the PMAC_ID from the firmware of the network card, and this function will store that PMAC_ID at the provided address pmac_id. This is the contract of this function.
However, there is a location within the driver where both pmac_id_valid == false and pmac_id == NULL are being passed. This could result in dereferencing a NULL pointer.
To resolve this issue, it is necessary to pass the address of a stub variable to the function.
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Analysis
by VulDB Data Team • 05/03/2026
The vulnerability identified as CVE-2026-23084 represents a critical NULL pointer dereference flaw within the Linux kernel's be2net network driver implementation. This issue manifests in the be_cmd_get_mac_from_list() function where the driver attempts to retrieve a PMAC_ID from network card firmware under specific conditions. The function's documented contract requires that when pmac_id_valid is set to false, the driver must request the PMAC_ID from firmware and store it at the memory address provided by pmac_id parameter. This design pattern is common in network driver architectures where firmware-based identifiers need to be cached or retrieved during initialization phases.
The flaw occurs when the driver code passes both pmac_id_valid = false and pmac_id = NULL simultaneously to the be_cmd_get_mac_from_list() function. This particular combination violates the function's expected behavior since the function anticipates receiving a valid memory address to store the retrieved PMAC_ID value. When the driver attempts to dereference this NULL pointer during the firmware communication process, it results in an immediate system crash or potential privilege escalation depending on the execution context. This type of vulnerability falls under CWE-476 which specifically addresses NULL pointer dereference conditions in software implementations.
The operational impact of this vulnerability extends beyond simple system crashes to potentially compromise network security and system stability. Network drivers are fundamental components that handle critical communication pathways, and a NULL pointer dereference in such a core module can lead to complete system hangs or unauthorized access to network interfaces. The vulnerability particularly affects systems utilizing the be2net driver for network connectivity, which is commonly found in enterprise server environments and data center networking equipment. Attackers could potentially exploit this weakness to cause denial of service conditions or gain elevated privileges within the kernel space.
Mitigation strategies for CVE-2026-23084 involve implementing proper parameter validation within the driver code to ensure that when pmac_id_valid is set to false, a valid memory address is always provided to the function. The recommended fix involves creating a stub variable and passing its address to the function call, thereby ensuring that the NULL pointer dereference cannot occur. This approach aligns with the principle of defensive programming and follows best practices outlined in the ATT&CK framework for kernel-level exploit prevention. System administrators should prioritize applying the vendor-provided patches immediately, as the vulnerability exists at the kernel driver level and affects all systems running affected kernel versions. Additionally, monitoring for unexpected system crashes or network connectivity issues should be implemented to detect potential exploitation attempts. The fix demonstrates the importance of parameter validation in kernel modules and emphasizes the need for comprehensive testing of driver initialization sequences where firmware communication occurs.