CVE-2026-23011

/// Technical description

In the Linux kernel, the following vulnerability has been resolved:

ipv4: ip_gre: make ipgre_header() robust

Analog to commit db5b4e39c4e6 ("ip6_gre: make ip6gre_header() robust")

Over the years, syzbot found many ways to crash the kernel

in ipgre_header() [1].

This involves team or bonding drivers ability to dynamically

change their dev->needed_headroom and/or dev->hard_header_len

In this particular crash mld_newpack() allocated an skb

with a too small reserve/headroom, and by the time mld_sendpack()

was called, syzbot managed to attach an ipgre device.

[1]

skbuff: skb_under_panic: text:ffffffff89ea3cb7 len:2030915468 put:2030915372 head:ffff888058b43000 data:ffff887fdfa6e194 tail:0x120 end:0x6c0 dev:team0

kernel BUG at net/core/skbuff.c:213 !

Oops: invalid opcode: 0000 [#1] SMP KASAN PTI

CPU: 1 UID: 0 PID: 1322 Comm: kworker/1:9 Not tainted syzkaller #0 PREEMPT(full)

Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025

Workqueue: mld mld_if

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References