Vulnerability in linux (CVE-2026-43083, CVSS 9.1)

Summary

vulnerability in linux (CVE-2026-43083). Confidential information can be exposed externally.

Original description

The description as published by the source.

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

net: ioam6: fix OOB and missing lock

When trace->type.bit6 is set:

if (trace->type.bit6) {
    ...
    queue = skb_get_tx_queue(dev, skb);
    qdisc = rcu_dereference(queue->qdisc);

This code can lead to an out-of-bounds access of the dev->_tx[] array
when is_input is true. In such a case, the packet is on the RX path and
skb->queue_mapping contains the RX queue index of the ingress device. If
the ingress device has more RX queues than the egress device (dev) has
TX queues, skb_get_queue_mapping(skb) will exceed dev->num_tx_queues.
Add a check to avoid this situation since skb_get_tx_queue() does not
clamp the index. This issue has also revealed that per queue visibility
cannot be accurate and will be replaced later as a new feature.

While at it, add missing lock around qdisc_qstats_qlen_backlog(). The
function __ioam6_fill_trace_data() is called from both softirq and
process contexts, hence the use of spin_lock_bh() here.

Source: NIST National Vulnerability Database NVD GitHub Advisory

AI summary

Written by an external AI model and may contain mistakes. Check the original description and references below before acting on it.

A vulnerability has been discovered in the Linux kernel that allows out-of-bounds memory access via network attacks. This can lead to system instability or service disruption. Instruct your IT team to check if your systems are affected and update to the recommended version. Prompt action is crucial to address such issues.

In the Linux kernel's ioam6 module, an out-of-bounds access can occur under specific conditions when trace->type.bit6 is set. The issue manifests when is_input is true, resulting in skb->queue_mapping exceeding the device's TX queue count. The resolution involved adding boundary checks in the skb_get_tx_queue() usage. Additionally, a missing lock around qdisc_qstats_qlen_backlog() led to the inclusion of spin_lock_bh(). The patch is applied in the latest commits of the Linux kernel repository.

❓ What is the problem

Out-of-bounds access in Linux kernel's ioam6 module

📍 Affected scope

ioam6.c in Linux kernel

🔥 Severity

Critical, CVSS 9.1

🔧 How to fix

Apply latest patches from the Linux kernel repository

🛡️ Workaround

Material did not specify any workarounds

🔍 Detection

Monitor for unusual kernel message logs or network traffic anomalies related to RX and TX queue mismatches

Related past incidents Similar incidents extracted from past CVEs

CVE-2020-12351

A Bluetooth vulnerability in the Linux kernel that allowed remote code execution due to malformed input leading to out-of-bounds access

CVE-2021-22555

A heap out-of-bounds write vulnerability in the Linux kernel's netfilter that allowed escalation via crafted network packets

CVE-2022-27208

An out-of-bounds write in the ioam6 module of Linux kernel prior to 5.18.13

If this happens at your company Expected impact per business scenario

📌 In an enterprise network environment

Can lead to system crashes or downtime impacting business operations and productivity.

📌 On cloud-based Linux systems

Services may become unavailable, affecting customers and revenue due to downtime.

📌 Embedded Linux systems in critical infrastructure

Could result in significant disruptions, compromising safety and operational continuity.

Recommended action

Update all affected systems to the latest Linux kernel version that includes the patch, and monitor for unusual network activity or kernel log messages related to this vulnerability.

Response actions

Concrete steps and command examples for SOC/SRE teams to execute in order

1
Identify exposure identify
```
Audit SBOM/dependencies for affected components.
```
依存マニフェストで影響コンポーネントを特定する。
7
Post-deployment verification verify
```
Confirm patched version is live in production
```
パッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番では Step 3 と同じログクエリでアラート再発が無いか継続監視。

Affected packages

Linux Kernel

[{"type":"ECOSYSTEM","events":[{"introduced":"5.17.0"},{"fixed":"6.18.24"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"6.19.14"}]}]

Fix status by distribution

Fixed packages published by each distribution for this CVE

BellSoft Alpaquita BELL-CVE-2026-43083 linux-lts
Debian DEBIAN-CVE-2026-43083 linux
Ubuntu UBUNTU-CVE-2026-43083 linux-hwe-edge

Vulnerability in linux (CVE-2026-43083)