CVE-2026-68440 in Linux
Summary
by MITRE • 08/12/2026
In the Linux kernel, the following vulnerability has been resolved:
net: txgbe: fix heap overflow when reading module EEPROM
txgbe_read_eeprom_hostif() always copies round_up(length, 4) bytes into the caller buffer, which ethtool allocates with exactly 'length' bytes. A non-4-aligned length therefore causes an out-of-bounds write. Copy only the remaining bytes on the final dword instead.
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Analysis
by VulDB Data Team • 08/12/2026
The vulnerability in question affects the Linux kernel's txgbe network driver where a heap overflow occurs during EEPROM reading operations through the host interface. This flaw exists within the txgbe_read_eeprom_hostif() function which demonstrates a classic buffer management error. The function consistently copies round_up(length, 4) bytes into buffers allocated by ethtool with exactly 'length' bytes, creating a mismatch that leads to out-of-bounds memory writes when the length parameter is not divisible by four.
The technical implementation flaw stems from improper boundary calculations in memory copying operations. When ethtool requests EEPROM data of arbitrary byte lengths, the driver allocates memory based on the exact requested length but then proceeds to copy additional bytes beyond the allocated buffer boundaries. This occurs because the function rounds up the copy length to the nearest 4-byte boundary without accounting for the actual buffer size constraints. The issue specifically manifests when dealing with non-4-aligned data lengths, where the extra bytes copied overwrite adjacent memory locations in the heap.
The operational impact of this vulnerability extends beyond simple memory corruption, potentially enabling attackers to execute arbitrary code or cause system instability through controlled memory overwrites. This heap overflow represents a critical security risk as it could be exploited by malicious actors to gain unauthorized access to the system or disrupt network operations. The vulnerability affects systems running Linux kernels with the txgbe driver, particularly those utilizing Intel 82599 and newer network adapters that rely on this specific driver implementation.
Mitigation strategies should focus on immediate kernel updates that address the buffer overflow condition through proper boundary checking and memory management. System administrators must ensure all affected kernels are patched to prevent exploitation, while monitoring for anomalous network behavior or system crashes that might indicate attempted exploitation. The fix requires modifying the txgbe_read_eeprom_hostif() function to calculate the exact number of bytes to copy based on remaining data after dword alignment rather than blindly copying rounded values. This approach aligns with common security practices outlined in CWE-121 and CWE-787 related to buffer overflow conditions, and addresses attack vectors classified under ATT&CK techniques involving privilege escalation through kernel exploitation.
The root cause analysis reveals fundamental issues in memory management practices within kernel space drivers where assumptions about data alignment lead to critical security vulnerabilities. This type of flaw typically requires comprehensive code review processes to identify similar patterns across other network drivers and kernel subsystems that might exhibit comparable buffer handling behaviors. The vulnerability demonstrates the importance of rigorous input validation and boundary checking in kernel-level operations, particularly when dealing with hardware interface protocols where external inputs can influence memory allocation and copying operations.