CVE-2026-98097 in Linux
Summary
by MITRE • 09/25/2026
In the Linux kernel, the following vulnerability has been resolved:
tipc: Dont send random pad bytes in RESET/ACTIVATE messages
The interface name is passed in a fixed length (TIPC_MAX_IF_NAME) buffer. Replace the strcpy(data, l->if_name) with memcpy() so that the pad bytes are actually written (l->if_name[] is zero padded)
rather than sending random bytes from the skb to the remote system.
Replace two other strcpy() with strscpy().
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Analysis
by VulDB Data Team • 09/25/2026
The Linux kernel's Transparent Inter-Process Communication, or TIPC subsystem, contained a critical information disclosure vulnerability related to how interface names were handled during RESET and ACTIVATE message construction. This flaw stemmed from an improper memory initialization practice within the network stack code responsible for formatting these control messages. Specifically, when preparing data to be transmitted over the network, the kernel utilized a fixed-length buffer defined by TIPC_MAX_IF_NAME to hold the local interface name. The original implementation relied on strcpy() to copy the variable-length string of the interface name into this buffer. Because strcpy() only copies characters up to and including the null terminator without filling the remainder of the destination buffer with zeros, any bytes remaining in the buffer after the copied string were left uninitialized. These uninitialized memory regions contained whatever data previously resided at that stack or heap location, effectively creating a leak of kernel memory contents into network packets sent to remote systems.
This vulnerability allows for an out-of-band information disclosure attack where an attacker with access to TIPC traffic can extract sensitive kernel memory content. By analyzing the RESET and ACTIVATE messages exchanged between nodes in a TIPC cluster, an adversary could observe random bytes appended after the actual interface name string. These pad bytes are not sanitized or zeroed out before transmission due to the use of strcpy() which does not guarantee null-padding for fixed-size buffers. Consequently, this constitutes a classic buffer over-read scenario where data beyond the intended logical boundary is exposed. The impact extends beyond mere curiosity; leaked kernel memory can reveal pointers, cryptographic keys, stack canaries, or other sensitive state information that aids in further exploitation of the system. This aligns with CWE-200, which covers Exposure of Sensitive Information to an Unauthorized Actor, and specifically relates to improper initialization leading to information leakage via network protocols.
The resolution involves a fundamental change in how string data is copied into fixed-size buffers within the TIPC subsystem. The primary fix replaces the strcpy() call used for copying the interface name with memcpy(). Since the source buffer l->if_name[] is already zero-padded by kernel allocation mechanisms, using memcpy() ensures that all bytes up to the maximum length are correctly transferred, including the necessary null terminators and padding zeros. This guarantees that no uninitialized memory from the socket buffer skb is transmitted over the network. Additionally, two other instances of strcpy() within the same code path were replaced with strscpy(). The strscpy function provides safer string copying by ensuring the destination buffer is always null-terminated and preventing potential buffer overflows if the source string exceeds the destination size. This dual approach addresses both the immediate information leak via pad bytes and reinforces general memory safety against overflow vulnerabilities.
From a defensive perspective, this incident highlights the importance of strict adherence to safe string handling practices in kernel development. The use of strcpy() is widely deprecated in modern secure coding standards due to its lack of bounds checking and failure to initialize remaining buffer space. Developers must prioritize functions like strscpy(), strncpy_s, or memcpy with explicit length calculations when dealing fixed-size buffers. For system administrators and security teams, ensuring that the Linux kernel is updated to a version containing this TIPC fix is essential to prevent potential information disclosure attacks in environments relying on Transparent Inter-Process Communication for high-performance cluster messaging. Monitoring network traffic for anomalous data patterns in control messages can also serve as an indicator of compromise if older vulnerable versions are still in operation, although the primary mitigation remains patching the underlying kernel code to eliminate the root cause of the uninitialized memory exposure.