Vulnerability in Linux kernel (CVE-2025-21692)
Summary
Vulnerability in Linux kernel (CVE-2025-21692). Successful exploitation can lead to full system takeover.
Original description
The description as published by the source.
In the Linux kernel, the following vulnerability has been resolved:
net: sched: fix ets qdisc OOB Indexing
Haowei Yan found that ets_class_from_arg() can
index an Out-Of-Bound class in ets_class_from_arg() when passed clid of
0. The overflow may cause local privilege escalation.
[ 18.852298] ------------[ cut here ]------------
[ 18.853271] UBSAN: array-index-out-of-bounds in net/sched/sch_ets.c:93:20
[ 18.853743] index 18446744073709551615 is out of range for type 'ets_class [16]'
[ 18.854254] CPU: 0 UID: 0 PID: 1275 Comm: poc Not tainted 6.12.6-dirty #17
[ 18.854821] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1 04/01/2014
[ 18.856532] Call Trace:
[ 18.857441]
[ 18.858227] dump_stack_lvl+0xc2/0xf0
[ 18.859607] dump_stack+0x10/0x20
[ 18.860908] __ubsan_handle_out_of_bounds+0xa7/0xf0
[ 18.864022] ets_class_change+0x3d6/0x3f0
[ 18.864322] tc_ctl_tclass+0x251/0x910
[ 18.864587] ? lock_acquire+0x5e/0x140
[ 18.865113] ? __mutex_lock+0x9c/0xe70
[ 18.866009] ? __mutex_lock+0xa34/0xe70
[ 18.866401] rtnetlink_rcv_msg+0x170/0x6f0
[ 18.866806] ? __lock_acquire+0x578/0xc10
[ 18.867184] ? __pfx_rtnetlink_rcv_msg+0x10/0x10
[ 18.867503] netlink_rcv_skb+0x59/0x110
[ 18.867776] rtnetlink_rcv+0x15/0x30
[ 18.868159] netlink_unicast+0x1c3/0x2b0
[ 18.868440] netlink_sendmsg+0x239/0x4b0
[ 18.868721] ____sys_sendmsg+0x3e2/0x410
[ 18.869012] ___sys_sendmsg+0x88/0xe0
[ 18.869276]…
Source: NIST National Vulnerability Database NVD GitHub Advisory
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-2025-21692 has been found in Linux kernel.
Successful exploitation can lead to full system takeover. CVSS score: 7.8/10.
What to do: apply the vendor's official patched release.
If unsure, ask your IT team or search "Linux kernel CVE-2025-21692" on the vendor's site.
CVE-2025-21692 (Linux kernel) — CWE-129 / CVSS v3 7.8
Attack vector: local / no user interaction
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.
A vulnerability (CWE-129) exists in Linux kernel.
Check the vendor advisory for the affected versions of Linux kernel.
Severity: High (CVSS 7.8/10). Successful exploitation can lead to full system takeover.
Update to the patched release per vendor advisory.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Audit SBOM/dependencies to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
-
1Identify exposure identify
Audit SBOM/dependencies for affected components.資産台帳・SBOM・依存マニフェストで Linux kernel を使っているサービスとバージョンを洗い出す。
-
2Post-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
Fix status by distribution
Fixed packages published by each distribution for this CVE
- BellSoft Alpaquita BELL-CVE-2025-21692 linux-lts Fixed in: 6.1.130-r0
- Debian DEBIAN-CVE-2025-21692 linux Fixed in: 5.10.234-1
- Ubuntu UBUNTU-CVE-2025-21692 linux-hwe-edge
References
- advisory nvd.nist.gov
- advisory github.com
- package git.kernel.org
- web git.kernel.org
- web git.kernel.org
- web git.kernel.org
- web git.kernel.org
- web git.kernel.org
- web git.kernel.org
- web git.kernel.org
- web lists.debian.org
- web lists.debian.org
- web cert-portal.siemens.com
- web cert-portal.siemens.com
- web github.com