CVE-2026-98097: Linux Kernel TIPC Buffer Overflow Vulnerability

CVE-2026-98097 Overview

CVE-2026-98097 is an information disclosure vulnerability in the Linux kernel's Transparent Inter-Process Communication (TIPC) protocol implementation. The flaw exists in how TIPC constructs RESET and ACTIVATE link state messages. The code uses strcpy() to copy the interface name into a fixed-length TIPC_MAX_IF_NAME buffer within a socket buffer (skb), which stops at the null terminator and leaves trailing bytes uninitialized. As a result, random stack or heap data from the skb is transmitted to remote peers instead of zero padding.

Critical Impact
Remote systems participating in TIPC link negotiation can receive uninitialized kernel memory contents in link state messages, enabling potential disclosure of sensitive kernel data across the network.

Affected Products

Linux kernel versions containing the vulnerable TIPC strcpy() usage in link state message construction
Systems with the TIPC kernel module (tipc.ko) loaded and active TIPC bearers configured
Distributions shipping the affected mainline kernel prior to the referenced stable commits

Discovery Timeline

2026-09-25 - CVE-2026-98097 published to the National Vulnerability Database (NVD)
2026-09-30 - Last updated in NVD database

Technical Details for CVE-2026-98097

Vulnerability Analysis

The vulnerability resides in the TIPC subsystem, which provides cluster-wide inter-process communication between Linux nodes. When TIPC constructs RESET or ACTIVATE link protocol messages, it embeds the local interface name in a fixed-length field sized to TIPC_MAX_IF_NAME. The original code used strcpy(data, l->if_name) to populate this field.

strcpy() terminates on the null byte and does not pad the remaining bytes of the destination buffer. Because the destination lives inside a socket buffer (skb) that was not pre-zeroed in that region, the trailing bytes retain whatever contents happened to occupy that memory. These bytes are then serialized onto the wire and sent to the remote TIPC peer. The fix replaces the call with memcpy() using the fixed buffer length, exploiting the fact that l->if_name[] is itself zero-padded. Two additional strcpy() calls are hardened to strscpy().

Root Cause

The root cause is improper initialization of a fixed-length protocol field, classified under information exposure through uninitialized memory. The developer assumed that writing a null-terminated string into a sized field was sufficient, but the serialization path transmits the full field length regardless of string termination. Any bytes beyond the interface name's null terminator leak directly to the remote system.

Attack Vector

Exploitation requires an attacker to participate in or passively observe TIPC link negotiation with a vulnerable node. In TIPC deployments spanning untrusted network segments or shared cluster fabrics, an adversary with the ability to establish a TIPC bearer, or to capture TIPC traffic, can collect the leaked bytes from each RESET or ACTIVATE message. Repeated link resets amplify the volume of leaked data available for reconstruction.

No verified public exploit code is available. See the upstream commit references in the Linux Kernel stable tree for the technical patch details.

Detection Methods for CVE-2026-98097

Indicators of Compromise

TIPC RESET or ACTIVATE messages on the wire whose interface-name field contains non-zero bytes after the null terminator of a legitimate interface name.
Unusual volumes of TIPC link reset events in kernel logs, which increase the exposure of leaked bytes.
TIPC bearers configured on untrusted or multi-tenant network segments where protocol frames can be captured.

Detection Strategies

Capture TIPC traffic with tcpdump or tshark filtering on EtherType 0x88ca and inspect the fixed interface-name field for entropy beyond the terminator.
Audit running kernels against the fixed stable commits referenced in the advisory to identify unpatched hosts.
Correlate tipc link command output and /var/log/kern.log link state transitions with network capture timestamps.

Monitoring Recommendations

Alert on new or unexpected loading of the tipc kernel module in environments that do not require it.
Track kernel version drift across cluster nodes to ensure uniform patch application.
Monitor TIPC bearer configuration changes through configuration management and auditd rules on tipc netlink activity.

How to Mitigate CVE-2026-98097

Immediate Actions Required

Apply the upstream Linux kernel patches referenced by the stable commit IDs 48033a89, 4ab29773, 81c600c2, and bee1459e.
Where TIPC is not required, unload the module with modprobe -r tipc and blacklist it to prevent reload.
Restrict TIPC bearers to trusted VLANs or dedicated cluster interconnects to limit exposure of leaked bytes.

Patch Information

The fix replaces the strcpy(data, l->if_name) call with memcpy() using the fixed TIPC_MAX_IF_NAME length so that the zero padding of l->if_name[] is actually written to the skb. Two other strcpy() call sites in the same subsystem are converted to strscpy() for defense in depth. Patch details are published in the Linux Kernel stable tree commits.

Workarounds

Disable TIPC entirely on hosts that do not use it by blacklisting the module in /etc/modprobe.d/.
Confine TIPC traffic to isolated physical or virtual network segments inaccessible to untrusted hosts.
Enforce link-layer encryption or IPsec on segments carrying TIPC frames to prevent passive capture of leaked bytes.

bash

# Prevent the TIPC module from loading on hosts that do not require it
echo 'install tipc /bin/true' | sudo tee /etc/modprobe.d/disable-tipc.conf
sudo modprobe -r tipc 2>/dev/null || true
lsmod | grep -q '^tipc' && echo 'TIPC still loaded' || echo 'TIPC disabled'