---
id: "CVE-2026-99282"
page: "https://infrastack.ai/live/CVE-2026-99282"
kind: "vulnerability"
aliases: ["CVE-2026-99282"]
title: "Linux kernel: traffic-control drop path lets a packet use freed memory"
severity: "unknown"
cvss: null
epss: null
exploited: false
status: "open"
category: "runtime"
products: []
ecosystems: []
tags: ["linux-kernel", "networking", "runtime", "vlan"]
not_affected_if: ["default-config", "teql-not-configured"]
published_at: "2026-11-07T14:17:03+00:00"
first_seen_at: "2026-11-07T14:47:40+00:00"
updated_at: "2026-11-07T14:49:45+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-99282", "first_seen_at": "2026-11-07T14:47:40+00:00"}]
exploit_sources: []
---

# Linux kernel: traffic-control drop path lets a packet use freed memory

Link for people: https://infrastack.ai/live/CVE-2026-99282 (this .md is for agents)

In the Linux kernel's teql traffic-control scheduler, a dropped packet on a VLAN slave can be used after it has been freed. The sources do not state what an attacker can gain from this.

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

## Timeline

- 2026-11-07T14:47:40+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-99282

## From the sources

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

net/sched: sch_teql: fix use-after-free on lower qdisc drop

The issue: teql_master_xmit() tests the slave's ndo_start_xmit() return
value against NETDEV_TX_OK alone. A slave that consumes the skb but
returns an error code (rc < NET_XMIT_MASK, e.g. NET_XMIT_DROP) is treated
as if the skb were still owned, so the loop restores skb->dev and calls
__skb_pull() on it. A VLAN slave returns the result of dev_queue_xmit()
from its ndo_start_xmit() (propagated since cbbef5e18307), and when the
lower qdisc drops the packet that value is NET_XMIT_DROP after the skb
has been freed, giving a use-after-free in teql_master_xmit().

The Fix: test for consumption with dev_xmit_complete(), which accepts
NETDEV_TX_OK and every rc < NET_XMIT_MASK, matching other callers that
need to distinguish consumed results from busy. Only NETDEV_TX_OK keeps
the packet counted in tx_packets/tx_bytes and advances the slave; a
consumed result that is neither a success nor NET_XMIT_CN ends the
attempt and is charged to tx_dropped, so lower-qdisc drops are no longer
reported as good transmits. NET_XMIT_CN is counted like success because
it can accompany acceptance of the current packet: pfifo_head_drop drops
the old head, enqueues the current skb and returns NET_XMIT_CN.

Conditions to recreate the bug:
With CONFIG_NET_SCH_TEQL,
CONFIG_VLAN_8021Q and CONFIG_DUMMY enabled, add lkrdummy0 (dummy) and
lkrvlan0 (VLAN id 37 on lkrdummy0); set a pfifo limit 0 root on lkrdummy0
and a teql0 root on lkrvlan0; bring teql0 up with an address and send one
UDP packet to it. The VLAN xmit returns NET_XMIT_DROP from the lower
qdisc while holding a freed skb.

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_Free to read, with fair use of about 60 pages a minute. For higher limits or API access: sales@infrastack.ai_