Vulnerability in Kernel (CVE-2026-23121)

Summary

Vulnerability in Kernel (CVE-2026-23121). Risk of unauthorized operations or information disclosure. Mitigation: upgrade to 5.10.249, 5.15.199, 6.1.162, 6.6.122, 6.12.68, 6.18.8 or later.

Original description

The description as published by the source.

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

mISDN: annotate data-race around dev->work

dev->work can re read locklessly in mISDN_read()
and mISDN_poll(). Add READ_ONCE()/WRITE_ONCE() annotations.

BUG: KCSAN: data-race in mISDN_ioctl / mISDN_read

write to 0xffff88812d848280 of 4 bytes by task 10864 on cpu 1:
misdn_add_timer drivers/isdn/mISDN/timerdev.c:175 [inline]
mISDN_ioctl+0x2fb/0x550 drivers/isdn/mISDN/timerdev.c:233
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:597 [inline]
__se_sys_ioctl+0xce/0x140 fs/ioctl.c:583
__x64_sys_ioctl+0x43/0x50 fs/ioctl.c:583
x64_sys_call+0x14b0/0x3000 arch/x86/include/generated/asm/syscalls_64.h:17
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xd8/0x2c0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff88812d848280 of 4 bytes by task 10857 on cpu 0:
mISDN_read+0x1f2/0x470 drivers/isdn/mISDN/timerdev.c:112
do_loop_readv_writev fs/read_write.c:847 [inline]
vfs_readv+0x3fb/0x690 fs/read_write.c:1020
do_readv+0xe7/0x210 fs/read_write.c:1080
__do_sys_readv fs/read_write.c:1165 [inline]
__se_sys_readv fs/read_write.c:1162 [inline]
__x64_sys_readv+0x45/0x50 fs/read_write.c:1162
x64_sys_call+0x2831/0x3000 arch/x86/include/generated/asm/syscalls_64.h:20
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xd8/0x2c0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

value…

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-2026-23121 has been found in Kernel.
Risk of unauthorized operations or information disclosure.
What to do: upgrade Kernel to 5.10.249, 5.15.199, 6.1.162, 6.6.122, 6.12.68, 6.18.8 or later.
If unsure, ask your IT team or search "Kernel CVE-2026-23121" on the vendor's site.

CVE-2026-23121 (Kernel)
Patched: 5.10.249, 5.15.199, 6.1.162, 6.6.122, 6.12.68, 6.18.8 — 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: ?. Risk of unauthorized operations or information disclosure.

🔧 How to fix

Update to 5.10.249, 5.15.199, 6.1.162, 6.6.122, 6.12.68, 6.18.8.

🛡️ 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 5.10.249, 5.15.199, 6.1.162, 6.6.122, 6.12.68, 6.18.8
```
ステージング環境で 5.10.249, 5.15.199, 6.1.162, 6.6.122, 6.12.68, 6.18.8 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":"2.6.27"},{"fixed":"5.10.249"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.11.0"},{"fixed":"5.15.199"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.16.0"},{"fixed":"6.1.162"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.2.0"},{"fixed":"6.6.122"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.7.0"},{"fixed":"6.12.68"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.18.8"}]}]

Fix status by distribution

Fixed packages published by each distribution for this CVE

BellSoft Alpaquita BELL-CVE-2026-23121 linux-lts Fixed in: 6.1.163-r0
Debian DEBIAN-CVE-2026-23121 linux Fixed in: 5.10.249-1
Ubuntu UBUNTU-CVE-2026-23121 linux