Vulnerability in Kernel (CVE-2026-23198)

Summary

Vulnerability in Kernel (CVE-2026-23198). Successful exploitation can lead to full system takeover. Mitigation: upgrade to 5.10.250, 5.15.200, 6.1.163, 6.6.124, 6.12.70, 6.18.10 or later.

Original description

The description as published by the source.

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

KVM: Don't clobber irqfd routing type when deassigning irqfd

When deassigning a KVM_IRQFD, don't clobber the irqfd's copy of the IRQ's
routing entry as doing so breaks kvm_arch_irq_bypass_del_producer() on x86
and arm64, which explicitly look for KVM_IRQ_ROUTING_MSI. Instead, to
handle a concurrent routing update, verify that the irqfd is still active
before consuming the routing information. As evidenced by the x86 and
arm64 bugs, and another bug in kvm_arch_update_irqfd_routing() (see below),
clobbering the entry type without notifying arch code is surprising and
error prone.

As a bonus, checking that the irqfd is active provides a convenient
location for documenting why KVM must not consume the routing entry for
an irqfd that is in the process of being deassigned: once the irqfd is
deleted from the list (which happens before the eventfd is detached), it
will no longer receive updates via kvm_irq_routing_update(), and so KVM
could deliver an event using stale routing information (relative to
KVM_SET_GSI_ROUTING returning to userspace).

As an even better bonus, explicitly checking for the irqfd being active
fixes a similar bug to the one the clobbering is trying to prevent: if an
irqfd is deactivated, and then its routing is changed,
kvm_irq_routing_update() won't invoke kvm_arch_update_irqfd_routing()
(because the irqfd isn't in the list). And so if the irqfd is in bypass
mode, IRQs will continue…

Source: OSV.dev (Open Source Vulnerabilities) NVD OSV

Auto-generated summary

Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.

A vulnerability tracked as CVE-2026-23198 has been found in Kernel.
Successful exploitation can lead to full system takeover.
What to do: upgrade Kernel to 5.10.250, 5.15.200, 6.1.163, 6.6.124, 6.12.70, 6.18.10 or later.
If unsure, ask your IT team or search "Kernel CVE-2026-23198" on the vendor's site.

CVE-2026-23198 (Kernel)
Attack vector: local / no user interaction
Patched: 5.10.250, 5.15.200, 6.1.163, 6.6.124, 6.12.70, 6.18.10 — apply immediately
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.

❓ What is the problem

A vulnerability (unclassified) exists in Kernel.

📍 Affected scope

Check the vendor advisory for the affected versions of Kernel.

🔥 Severity

Severity: ?. Successful exploitation can lead to full system takeover.

🔧 How to fix

Update to 5.10.250, 5.15.200, 6.1.163, 6.6.124, 6.12.70, 6.18.10.

🛡️ Workaround

Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.

🔍 Detection

Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'Kernel' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.

Response actions

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

1
Identify exposure identify
```
grep -r 'Kernel' . | grep -v node_modules
```
リポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で Kernel を grep し、稼働しているサービス・バージョンを把握する。
2
Apply patch patch
```
Upgrade Kernel to 5.10.250, 5.15.200, 6.1.163, 6.6.124, 6.12.70, 6.18.10
```
ステージング環境で 5.10.250, 5.15.200, 6.1.163, 6.6.124, 6.12.70, 6.18.10 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。
3
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。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。

Affected packages

Linux Kernel

[{"type":"ECOSYSTEM","events":[{"introduced":"4.4.0"},{"fixed":"5.10.250"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.11.0"},{"fixed":"5.15.200"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.16.0"},{"fixed":"6.1.163"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.2.0"},{"fixed":"6.6.124"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.7.0"},{"fixed":"6.12.70"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.18.10"}]}]

Fix status by distribution

Fixed packages published by each distribution for this CVE

BellSoft Alpaquita BELL-CVE-2026-23198 linux-lts Fixed in: 6.1.163-r0
Debian DEBIAN-CVE-2026-23198 linux Fixed in: 5.10.251-1
Ubuntu UBUNTU-CVE-2026-23198 linux-aws