CVE-2026-89555
A critical bug in the Linux kernel’s MPLS handling can cause a use‑after‑free error when processing certain Geneve packets. The flaw occurs when the kernel expands the packet buffer, leaving a stale pointer that can be dereferenced. If exploited, it could allow an attacker to crash the kernel or potentially gain elevated privileges.
An official fix is available, so this entry is kept for 30 days and then removed automatically.
Who is affected
All Linux kernel users that run a kernel version before the patch that fixes the MPLS use‑after‑free bug, including systems that process Geneve packets over MPLS multipath.
Real-world impact
An attacker could crash the kernel or potentially execute arbitrary code with kernel privileges by sending specially crafted Geneve packets through an MPLS multipath setup.
Why this severity
The CVSS score of 9.8 reflects the high impact on confidentiality, integrity, and availability, and the fact that the vulnerability can be exploited remotely without authentication or user interaction.
What to do about it
- 01Upgrade the Linux kernel to the latest patched release (e.g., via your distribution’s package manager).
- 02Reboot the system to load the new kernel.
NVD description indicates the vulnerability has been resolved in the Linux kernel.
Timeline
- Sep 11, 2026 · 2d agoPublishedDisclosed and added to the National Vulnerability Database.
- Sep 13, 2026 · 7h agoOfficial fix availableA vendor patch or mitigation now exists — see the remediation steps above.