CVE-2023-53517
A flaw in the Linux kernel’s TIPC module allows a malicious peer to send a very small MTU value during link negotiation, causing an integer overflow that can crash the kernel. The bug is triggered by an attacker who sends an Activate message with an MTU of 4, leading to a huge memory allocation and a kernel panic. The issue has been fixed in a kernel patch that validates the MTU before updating it.
An official fix is available, so this entry is kept for 30 days and then removed automatically.
Who is affected
Linux kernel users running versions that include the TIPC module before the patch, notably kernel 6.4 and earlier. Any system that accepts TIPC connections is potentially affected.
Real-world impact
An attacker can cause the kernel to crash, resulting in a denial‑of‑service that brings the entire system down. The crash can be triggered remotely without authentication, making it a critical threat to uptime and availability.
Why this severity
The CVSS score of 9.8 reflects that the vulnerability is exploitable over the network (AV:N), requires no privileges (PR:N), has no user interaction (UI:N), and can lead to complete compromise of confidentiality, integrity, and availability (C:H/I:H/A:H).
What to do about it
- 011. Verify your current kernel version with `uname -r`.
- 022. If your kernel is older than 6.4, upgrade to Linux kernel 6.4 or a later release that includes the TIPC MTU validation patch.
- 033. Reboot the system to load the updated kernel.
NVD-referenced vendor advisory
Timeline
- Oct 1, 2025 · Oct 1, 2025PublishedDisclosed and added to the National Vulnerability Database.
- Aug 4, 2026 · 1d agoAdvisory updatedThe NVD record was last revised.
- Aug 4, 2026 · 1d agoOfficial fix availableA vendor patch or mitigation now exists — see the remediation steps above.