Linux Kernel IPv6 AH Routing Header Integer Underflow Local Privilege Escalation Vulnerability

October 29th, 2026
ZDI-26-834 ZDI-CAN-31769

CVE ID

CVE-2026-80844

CVSS Score

8.8 AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

Affected Vendors

Linux

Affected Products

Kernel

Vulnerability Details

This vulnerability allows local attackers to escalate privileges on affected installations of Linux Kernel. An attacker must first obtain the ability to execute low-privileged code on the target system in order to exploit this vulnerability.

The specific flaw exists within the parsing of ipv6_rt_hdr headers. The issue results from the lack of proper validation of user-supplied data, which can result in an integer underflow before allocating a buffer. An attacker can leverage this vulnerability to escalate privileges and execute arbitrary code in the context of the kernel.

Additional Details

Linux has issued an update to correct this vulnerability. More details can be found at:
https://github.com/torvalds/linux/commit/7bad4bda74dc4713f398d3b7624ff05478e3a568

Disclosure Timeline

  • 2026-07-16 - Vulnerability reported to vendor
  • 2026-10-29 - Coordinated public release of advisory
  • 2026-10-29 - Advisory Updated

Credit

ELDEN

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