CVE-2026-64000 in Linux
Summary
by MITRE • 07/19/2026
In the Linux kernel, the following vulnerability has been resolved:
net: hsr: fix potential OOB access in supervision frame handling
Ensure the entire TLV header is linearized before access by adding sizeof(struct hsr_sup_tlv) to the pskb_may_pull() calls. Without this, a truncated frame could cause an out-of-bounds access.
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Analysis
by VulDB Data Team • 07/19/2026
The vulnerability identified in the Linux kernel's HSR (High-availability Seamless Redundancy) implementation represents a critical out-of-bounds memory access flaw that could potentially lead to system instability or privilege escalation. This issue specifically affects the supervision frame handling mechanism within the HSR protocol implementation, which is designed to provide transparent failover for industrial network applications. The vulnerability stems from insufficient validation of TLV (Type-Length-Value) header structures before memory access operations, creating a scenario where malformed network frames could trigger unintended memory access patterns.
The technical flaw occurs when the kernel processes HSR supervision frames without ensuring that the complete TLV header structure is accessible in contiguous memory. The pskb_may_pull() function is responsible for pulling data from the packet buffer into linear memory space, but the implementation fails to account for the full size of the hsr_sup_tlv structure during this operation. This omission means that when processing truncated network frames, the kernel may attempt to access memory locations beyond the actual frame boundaries, resulting in out-of-bounds memory access patterns that could be exploited by malicious actors. The vulnerability is classified under CWE-129 as an insufficient validation of length of input data, specifically manifesting as an out-of-bounds read operation.
From an operational standpoint, this vulnerability poses significant risks to industrial control systems and network infrastructure that rely on HSR protocols for redundancy and failover mechanisms. Attackers could potentially craft malicious network frames that trigger the out-of-bounds access condition, leading to system crashes, denial of service conditions, or in severe cases, arbitrary code execution within kernel space. The impact extends beyond simple disruption as these systems often operate in critical environments where availability is paramount, making such vulnerabilities particularly dangerous in industrial IoT deployments and real-time control networks.
The mitigation strategy involves ensuring that the entire TLV header structure is linearized before any access operations occur by explicitly adding sizeof(struct hsr_sup_tlv) to the pskb_may_pull() calls. This approach aligns with established security practices for kernel memory management and follows the principle of least privilege in network protocol handling. The fix directly addresses the root cause by guaranteeing that sufficient packet data is available in linear memory before attempting to parse structured headers, thereby preventing the out-of-bounds access scenario. This remediation technique corresponds to ATT&CK tactic T1068 which involves exploiting vulnerabilities in system processes and kernel-level operations, making it essential for maintaining system integrity in industrial network environments where HSR protocols are deployed.
Security researchers have noted that similar vulnerabilities in network protocol implementations often stem from insufficient input validation and memory management practices within kernel space. The fix implemented here demonstrates proper defensive programming techniques that should be adopted across similar protocol handlers to prevent analogous issues in other network subsystems. This vulnerability highlights the importance of rigorous testing with malformed inputs and proper boundary checking in kernel network code, particularly for industrial protocols that are increasingly integrated into broader network infrastructures. The resolution ensures that memory access patterns remain within defined boundaries regardless of input frame characteristics, thereby maintaining system stability and preventing potential exploitation scenarios that could compromise industrial control systems relying on HSR redundancy mechanisms.