---
id: "CVE-2026-99027"
kind: "vulnerability"
aliases: ["CVE-2026-99027"]
title: "Linux kernel: team driver reuses freed packet buffer, crashing the kernel"
severity: "unknown"
cvss: null
epss: null
exploited: false
status: "open"
category: "runtime"
products: []
ecosystems: []
tags: ["linux-kernel", "network-teaming", "runtime", "self-hosted"]
not_affected_if: ["no-team-driver"]
published_at: "2026-10-23T13:17:25+00:00"
first_seen_at: "2026-10-23T21:57:33+00:00"
updated_at: "2026-10-25T04:54:27+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-99027", "first_seen_at": "2026-10-23T21:57:33+00:00"}]
---

# Linux kernel: team driver reuses freed packet buffer, crashing the kernel

The Linux kernel's team network driver kept using a packet buffer after the lower queue had already freed it, a use-after-free. The sources show a KASAN report with a kernel panic, and nothing on what an attacker can do beyond crashing the machine.

_Summary, check and fix written by a model from the sources; labelled as such._

## How to check

- Run `uname -r` and compare against the fixed kernel build listed by your distribution's advisory
- Check whether the team driver is loaded with `lsmod | grep team`

## Fix

- Update the Linux kernel to a build that includes the upstream commit 'net: team: stop reusing skb after queue override'; the sources do not list fixed version numbers

## Timeline

- 2026-10-23T21:57:33+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-99027

## From the sources

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

net: team: stop reusing skb after queue override

A nonzero dev_queue_xmit() result does not return ownership of the skb.
When an override port's qdisc drops it, the queue override helper used to
try another port or the mode transmit op with the freed skb.

Return the handoff decision separately from transmit success. Select only
the first override port under RCU and stop after handing it the skb,
regardless of the lower transmit result. Keep the existing success and
drop accounting.

  BUG: KASAN: slab-use-after-free in sk_skb_reason_drop
  Write of size 4 by task poc/5040
  sk_skb_reason_drop (net/core/skbuff.c:1240)
  dev_kfree_skb_any_reason (net/core/dev.c:3470)
  ab_transmit (drivers/net/team/team_mode_activebackup.c:49)
  team_xmit (drivers/net/team/team_core.c:1849)
  __dev_direct_xmit (net/core/dev.c:4934)
  Freed by task 5040:
  __tcf_kfree_skb_list (net/sched/sch_generic.c:43)
  __dev_queue_xmit (net/core/dev.c:4831)
  team_xmit (drivers/net/team/team_core.c:1846)
  Kernel panic - not syncing: KASAN: panic_on_warn set ...

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