CVE-2026-72013 in Linux
Summary
by MITRE • 08/15/2026
In the Linux kernel, the following vulnerability has been resolved:
riscv: Prevent NULL pointer dereference in machine_kexec_prepare()
A NULL pointer dereference issue is noticed in riscv's machine_kexec_prepare(), where image->segment[i].buf might be NULL and
copied unchecked.
The NULL buf comes from ima_add_kexec_buffer(), where kbuf is added by kexec_add_buffer(), but kbuf.buffer is NULL, then it is copied without a check in machine_kexec_prepare():
kexec_file_load -> kimage_file_alloc_init() -> kimage_file_prepare_segments() -> ima_add_kexec_buffer() -> kexec_add_buffer() -> machine_kexec_prepare() -> memcpy()
Address this by adding a check before the data copy attempt.
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Analysis
by VulDB Data Team • 08/15/2026
The vulnerability exists within the riscv architecture implementation of the Linux kernel's kexec functionality, specifically in the machine_kexec_prepare() function where a NULL pointer dereference can occur during system kernel execution. This flaw represents a critical security issue that could potentially allow malicious actors to crash the system or execute arbitrary code through improper memory handling during the kernel loading process. The vulnerability stems from inadequate input validation when processing memory segments during kexec operations, creating an exploitable condition that violates fundamental security principles of memory safety.
The technical root cause manifests when the ima_add_kexec_buffer() function processes kernel buffer data, where kexec_add_buffer() is invoked to add a kernel buffer through the kexec_add_buffer() call chain. During this process, the kbuf.buffer field becomes NULL, yet this NULL value propagates unchecked through the function call stack directly to machine_kexec_prepare(). The function attempts to perform a memcpy operation without validating whether the source buffer pointer is valid, creating a classic NULL pointer dereference condition that can lead to system crashes or privilege escalation. This vulnerability aligns with CWE-476 which specifically addresses NULL pointer dereferences and represents a failure to implement proper input validation mechanisms.
The operational impact of this vulnerability extends beyond simple system instability as it affects the kernel's ability to safely handle memory segments during kexec operations, which are critical for system recovery and live patching scenarios. An attacker could exploit this condition by crafting malicious kexec load requests that force the system into a state where NULL pointers are dereferenced, potentially leading to denial of service conditions or more severe exploitation depending on system configuration. The vulnerability affects systems running riscv architecture kernels when kexec functionality is utilized, making it particularly concerning for embedded systems and server environments that rely on kernel crash recovery mechanisms.
Mitigation strategies should focus on implementing proper NULL pointer validation before any memory copy operations within the machine_kexec_prepare() function to prevent the execution path from proceeding when buffer data is invalid. The recommended fix involves adding explicit checks to verify that image->segment[i].buf is not NULL before attempting the memcpy operation, which directly addresses the root cause identified in the vulnerability description. Security hardening measures should also include implementing comprehensive input validation for all kernel buffer operations and establishing proper error handling procedures that prevent NULL values from propagating through critical execution paths. This approach aligns with defensive programming practices and helps satisfy security requirements outlined in various cybersecurity frameworks while addressing the specific ATT&CK technique of privilege escalation through kernel memory corruption vulnerabilities.