Linux Kernel: security vulnerability (CVE-2025-21862)
Published Last modified Sources: Siemens ProductCERT, BSI, SUSE, Debian LTS, Debian, CVE.org, Msrc Update Guide, EUVD
What is affected, what to do
In the Linux kernel, the following vulnerability has been resolved: drop_monitor: fix incorrect initialization order Syzkaller reports the following bug: BUG: spinlock bad magic on CPU#1, syz-executor.0/7995 lock: 0xffff88805303f3e0, .magic: 00000000, .owner: <none>/-1, .owner_cpu: 0 CPU: 1 PID: 7995 Comm: syz-executor.0 Tainted: G E 5.10.209+ #1 Hardware name: VMware, Inc. VMware Virtual Platform/440BX Desktop Reference Platform, BIOS 6.00 11/12/2020 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x119/0x179 lib/dump_stack.c:118 debug_spin_lock_before kernel/locking/spinlock_debug.c:83 [inline] do_raw_spin_lock+0x1f6/0x270 kernel/locking/spinlock_debug.c:112 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:117 [inline] _raw_spin_lock_irqsave+0x50/0x70 kernel/locking/spinlock.c:159 reset_per_cpu_data+0xe6/0x240 [drop_monitor] net_dm_cmd_trace+0x43d/0x17a0 [drop_monitor] genl_family_rcv_msg_doit+0x22f/0x330 net/netlink/genetlink.c:739 genl_family_rcv_msg net/netlink/genetlink.c:783 [inline] genl_rcv_msg+0x341/0x5a0 net/netlink/genetlink.c:800 netlink_rcv_skb+0x14d/0x440 net/netlink/af_netlink.c:2497 genl_rcv+0x29/0x40 net/netlink/genetlink.c:811 netlink_unicast_kernel net/netlink/af_netlink.c:1322 [inline] netlink_unicast+0x54b/0x800 net/netlink/af_netlink.c:1348 netlink_sendmsg+0x914/0xe00 net/netlink/af_netlink.c:1916 sock_sendmsg_nosec net/socket.c:651 [inline] __sock_sendmsg+0x157/0x190 net/socket.c:663 ____sys_sendmsg+0x712/0x870 net/socket.c:2378 ___sys_sendmsg+0xf8/0x170 net/socket.c:2432 __sys_sendmsg+0xea/0x1b0 net/socket.c:2461 do_syscall_64+0x30/0x40 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x62/0xc7 RIP: 0033:0x7f3f9815aee9 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b0 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f3f972bf0c8 EFLAGS: 00000246 ORIG_RAX: 000000000000002e RAX: ffffffffffffffda RBX: 00007f3f9826d050 RCX: 00007f3f9815aee9 RDX: 0000000020000000 RSI: 0000000020001300 RDI: 0000000000000007 RBP: 00007f3f981b63bd R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 000000000000006e R14: 00007f3f9826d050 R15: 00007ffe01ee6768 If drop_monitor is built as a kernel module, syzkaller may have time to send a netlink NET_DM_CMD_START message during the module loading.
Update Linux Kernel to version 5.4.291, Linux Kernel to version 5.10.235, Linux Kernel to version 5.15.179.
- Affected
- Linux Kernel
lt 2.6.30..5.4.291 - Linux Kernel
lt 5.5..5.10.235 - Linux Kernel
lt 5.11..5.15.179 - Linux Kernel
lt 5.16..6.1.130 - Linux Kernel
lt 6.2..6.6.80 - Linux Kernel
lt 6.7..6.12.17 - Linux Kernel
lt 6.13..6.13.5
- Linux Kernel
- Fixed in
- Linux Kernel
5.4.291 - Linux Kernel
5.10.235 - Linux Kernel
5.15.179 - Linux Kernel
6.1.130 - Linux Kernel
6.6.80 - Linux Kernel
6.12.17 - Linux Kernel
6.13.5 - Linux Kernel
6.14
- Linux Kernel
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Metrics
5.5
Priority
XIEM Effective CVSS: highest available CVSS rating from NVD and vendor data.
Source: NVD, CVSS v3
5.5
CVSS v3
Severity Medium on the scale from 0 to 10.
Source: Siemens ProductCERT, BSI, SUSE, Debian LTS, Debian, CVE.org, Msrc Update Guide, EUVD
0.3 %
EPSS score
Low — model estimates < 1% exploitation likelihood.
Source: FIRST EPSS, percentile 16.7
Show all metrics
- Severity
- Medium
Priority (0–325)
The priority score is a consolidated metric that condenses several individual signals into a single, action-guiding ranking: technical severity (CVSS), exploitation likelihood (EPSS), known-exploited status (KEV) and the context of the affected asset. The aim is to answer the only truly important question in vulnerability management: what first?
Read in glossary- 37.88 Methodology
Exploit maturity
An exploit is code or a technique that specifically uses a concrete vulnerability to force unintended behaviour — such as executing code or escalating privileges. It is the tool that turns a theoretical flaw into a practical attack.
Read in glossary- no public PoC known
XIEM Effective CVSS
XIEM® is the tiered managed-security operating model from NEOSEC and a registered trademark of NEOSEC GmbH. It extends classic SIEM — the central collection, normalisation and correlation of security-relevant events — with endpoint forensics, network visibility and deception technology, and consolidates them into three building tiers: Sentry, Orchestrate and Command.
Read in glossary- 5.5 Methodology
CVSS v3
CVSS is the globally established, open standard for assessing the technical severity of a vulnerability on a scale from 0 to 10. It describes how easily a flaw can be exploited and what damage it can cause — but not how likely its actual exploitation is. CVSS and the complementary EPSS deliberately answer different questions.
Read in glossary- 5.5
EPSS score
The EPSS score is the absolute model output for an individual vulnerability: the estimated probability of real-world exploitation within the next 30 days, expressed as a value between 0 and 1 (i.e. 0 % to 100 %). A score of 0.42 means „the model estimates a 42 % chance of real-world exploitation within 30 days“.
Read in glossary- 0.3 %
- Low — model estimates < 1% exploitation likelihood.
EPSS percentile
The EPSS percentile is the relative position of a vulnerability within all EPSS-scored CVEs, expressed as a value between 0 and 1. A percentile of 0.90 means „this CVE has a higher EPSS score than 90 % of all other scored CVEs“. Unlike the EPSS score, it is not a probability — but a positioning within a ranking.
Read in glossary- 16.7
- Elevated — this CVE ranks above at least 10% of all CVEs scored today.
KEV status
The KEV catalogue is a list maintained by the US authority CISA of vulnerabilities for which active exploitation in the wild has been confirmed. It answers not the question „how severe?“ but „is it already being attacked?“ — thereby sharply prioritising patching.
Read in glossary- —
- Published
- CISA assessment (SSVC)
- Exploitation: none known · not automatable · Technical impact: partial
- Source: CISA Vulnrichment, as of 1 October 2025
CWE
CWE is a catalogue of typical weakness types in software and hardware — such as flawed input validation, unsafe memory handling or poor authentication. Where a CVE names a concrete vulnerability in a concrete product, a CWE describes the underlying class of defect.
Read in glossary- CWE-908
Detection rules
No NEOSEC detection rule is available for this vulnerability yet.
Classification under NIS2 and CRA
Rule-based classification from exploitation status and severity. It does not replace a case-by-case assessment.
NIS2
NIS2 is EU Directive (EU) 2022/2555 to raise the level of cybersecurity across the Union. It substantially broadens obligations compared with the first NIS directive: more sectors, mandatory risk management, staged reporting duties and personal accountability of senior management.
Read in glossary- Handle the vulnerability in regular vulnerability handling under Art. 21(2)(e) NIS2.
CRA
The CRA is EU Regulation (EU) 2024/2847 setting horizontal cybersecurity requirements for „products with digital elements“ — from industrial controllers and software to connected consumer devices. For the first time manufacturers must ensure security across the entire product lifecycle, handle vulnerabilities and provide security updates.
Read in glossary- From 11.12.2027, Annex I Part II CRA requires manufacturers of affected products with digital elements to handle vulnerabilities without delay and provide security updates.
ISO/IEC 27001
ISO/IEC 27001 is the internationally leading standard for an information security management system (ISMS). It describes a risk-based, process-oriented framework to systematically plan, implement, review and improve information security.
Read in glossary- Control A.8.8, management of technical vulnerabilities: assess relevance to your systems, plan remediation and keep evidence.
Description
In the Linux kernel, the following vulnerability has been resolved: drop_monitor: fix incorrect initialization order Syzkaller reports the following bug: BUG: spinlock bad magic on CPU#1, syz-executor.0/7995 lock: 0xffff88805303f3e0, .magic: 00000000, .owner: <none>/-1, .owner_cpu: 0 CPU: 1 PID: 7995 Comm: syz-executor.0 Tainted: G E 5.10.209+ #1 Hardware name: VMware, Inc. VMware Virtual Platform/440BX Desktop Reference Platform, BIOS 6.00 11/12/2020 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x119/0x179 lib/dump_stack.c:118 debug_spin_lock_before kernel/locking/spinlock_debug.c:83 [inline] do_raw_spin_lock+0x1f6/0x270 kernel/locking/spinlock_debug.c:112 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:117 [inline] _raw_spin_lock_irqsave+0x50/0x70 kernel/locking/spinlock.c:159 reset_per_cpu_data+0xe6/0x240 [drop_monitor] net_dm_cmd_trace+0x43d/0x17a0 [drop_monitor] genl_family_rcv_msg_doit+0x22f/0x330 net/netlink/genetlink.c:739 genl_family_rcv_msg net/netlink/genetlink.c:783 [inline] genl_rcv_msg+0x341/0x5a0 net/netlink/genetlink.c:800 netlink_rcv_skb+0x14d/0x440 net/netlink/af_netlink.c:2497 genl_rcv+0x29/0x40 net/netlink/genetlink.c:811 netlink_unicast_kernel net/netlink/af_netlink.c:1322 [inline] netlink_unicast+0x54b/0x800 net/netlink/af_netlink.c:1348 netlink_sendmsg+0x914/0xe00 net/netlink/af_netlink.c:1916 sock_sendmsg_nosec net/socket.c:651 [inline] __sock_sendmsg+0x157/0x190 net/socket.c:663 ____sys_sendmsg+0x712/0x870 net/socket.c:2378 ___sys_sendmsg+0xf8/0x170 net/socket.c:2432 __sys_sendmsg+0xea/0x1b0 net/socket.c:2461 do_syscall_64+0x30/0x40 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x62/0xc7 RIP: 0033:0x7f3f9815aee9 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b0 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f3f972bf0c8 EFLAGS: 00000246 ORIG_RAX: 000000000000002e RAX: ffffffffffffffda RBX: 00007f3f9826d050 RCX: 00007f3f9815aee9 RDX: 0000000020000000 RSI: 0000000020001300 RDI: 0000000000000007 RBP: 00007f3f981b63bd R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 000000000000006e R14: 00007f3f9826d050 R15: 00007ffe01ee6768 If drop_monitor is built as a kernel module, syzkaller may have time to send a netlink NET_DM_CMD_START message during the module loading. This will call the net_dm_monitor_start() function that uses a spinlock that has not yet been initialized. To fix this, let's place resource initialization above the registration of a generic netlink family. Found by InfoTeCS on behalf of Linux Verification Center (linuxtesting.org) with Syzkaller.
Source: siemens_advisory, BSI CSAF, BSI WID Portal, suse_csaf, Debian LTS Advisories, Debian Security Advisories, cvelistv5, NVD (NIST), Microsoft Security Update Guide, CVE.org (MITRE), ENISA EUVD
Affected products
The following versions are affected. Older releases of the same product line are also vulnerable unless stated otherwise.
| Affected versions | Fixed in | ||
|---|---|---|---|
| Linux | Linux |
|
|
| Dell | Secure Connect Gateway |
|
|
| Siemens | SIMATIC S7 |
|
|
Vendors and products
Affected operating systems
| Linux | debian | linux | bookworm |
| Linux | debian | linux | bullseye |
| Linux | debian | linux-6.1 | bullseye |
| Linux | linux | linux_kernel | 6.14 |
| Linux | linux | linux_kernel | — |
Weakness classes (CWE)
CWE-908Use of Uninitialized Resource
Base
The product uses or accesses a resource that has not been initialized.
Entry at MITRE CWE-908
References & sources
- git.kernel.orgstable/c/6e9e0f224ffd8b819da3ea247dda404795fdd182
- git.kernel.orgstable/c/29f9cdcab3d96d5207a5c92b52c40ad75e5915d8
- git.kernel.orgstable/c/872c7c7e57a746046796ddfead529c9d37b9f6b4
- git.kernel.orgstable/c/fcfc00bfec7bb6661074cb21356d05a4c9470a3c
- git.kernel.orgstable/c/0efa6c42f81c60d8f72ba7f5ed8d4fec8c526282
- git.kernel.orgstable/c/b7859e8643e75619b2705b4fcac93ffd94d72b4a
- git.kernel.orgstable/c/219a47d0e6195bd202f22855e35f25bd15bc4d58
- git.kernel.orgstable/c/07b598c0e6f06a0f254c88dafb4ad50f8a8c6eea
- lists.debian.orgdebian-lts-announce/2025/05/msg00045.html
- lists.debian.orgdebian-lts-announce/2025/05/msg00030.html
- Siemens ProductCERTproductcert/html/ssa-265688.html
- Siemens ProductCERTproductcert/html/ssa-082556.html
- Siemens ProductCERTproductcert/html/ssa-784472.html
Changes to this CVE
Who changed this CVE and when: NVD (analysis, affected products, CVSS), the CVE publisher (CNA) and additional providers such as CISA (ADP).
Record modifiedLinux
New references:- https://git.kernel.org/stable/c/07b598c0e6f06a0f254c88dafb4ad50f8a8c6eea
- https://git.kernel.org/stable/c/0efa6c42f81c60d8f72ba7f5ed8d4fec8c526282
- https://git.kernel.org/stable/c/219a47d0e6195bd202f22855e35f25bd15bc4d58
- https://git.kernel.org/stable/c/29f9cdcab3d96d5207a5c92b52c40ad75e5915d8
and 4 more references
Show 24 original changes
Individual changes of this event as published by NVD Type Action Before After Reference added —https://git.kernel.org/stable/c/07b598c0e6f06a0f254c88dafb4ad50f8a8c6eeaReference added —https://git.kernel.org/stable/c/0efa6c42f81c60d8f72ba7f5ed8d4fec8c526282Reference added —https://git.kernel.org/stable/c/219a47d0e6195bd202f22855e35f25bd15bc4d58Reference added —https://git.kernel.org/stable/c/29f9cdcab3d96d5207a5c92b52c40ad75e5915d8Reference added —https://git.kernel.org/stable/c/6e9e0f224ffd8b819da3ea247dda404795fdd182Reference added —https://git.kernel.org/stable/c/872c7c7e57a746046796ddfead529c9d37b9f6b4Reference added —https://git.kernel.org/stable/c/b7859e8643e75619b2705b4fcac93ffd94d72b4aReference added —https://git.kernel.org/stable/c/fcfc00bfec7bb6661074cb21356d05a4c9470a3cReference removed https://git.kernel.org/stable/c/07b598c0e6f06a0f254c88dafb4ad50f8a8c6eea—Reference removed https://git.kernel.org/stable/c/0efa6c42f81c60d8f72ba7f5ed8d4fec8c526282—Reference removed https://git.kernel.org/stable/c/219a47d0e6195bd202f22855e35f25bd15bc4d58—Reference removed https://git.kernel.org/stable/c/29f9cdcab3d96d5207a5c92b52c40ad75e5915d8—Reference removed https://git.kernel.org/stable/c/6e9e0f224ffd8b819da3ea247dda404795fdd182—Reference removed https://git.kernel.org/stable/c/872c7c7e57a746046796ddfead529c9d37b9f6b4—Reference removed https://git.kernel.org/stable/c/b7859e8643e75619b2705b4fcac93ffd94d72b4a—Reference removed https://git.kernel.org/stable/c/fcfc00bfec7bb6661074cb21356d05a4c9470a3c—Reference type removed https://git.kernel.org/stable/c/07b598c0e6f06a0f254c88dafb4ad50f8a8c6eea Types: Patch—Reference type removed https://git.kernel.org/stable/c/0efa6c42f81c60d8f72ba7f5ed8d4fec8c526282 Types: Patch—Reference type removed https://git.kernel.org/stable/c/219a47d0e6195bd202f22855e35f25bd15bc4d58 Types: Patch—Reference type removed https://git.kernel.org/stable/c/29f9cdcab3d96d5207a5c92b52c40ad75e5915d8 Types: Patch—Reference type removed https://git.kernel.org/stable/c/6e9e0f224ffd8b819da3ea247dda404795fdd182 Types: Patch—Reference type removed https://git.kernel.org/stable/c/872c7c7e57a746046796ddfead529c9d37b9f6b4 Types: Patch—Reference type removed https://git.kernel.org/stable/c/b7859e8643e75619b2705b4fcac93ffd94d72b4a Types: Patch—Reference type removed https://git.kernel.org/stable/c/fcfc00bfec7bb6661074cb21356d05a4c9470a3c Types: Patch—Source identifier: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
Record modifiedCVE Program
Show 4 original changes
Individual changes of this event as published by NVD Type Action Before After Reference added —https://lists.debian.org/debian-lts-announce/2025/05/msg00030.htmlReference added —https://lists.debian.org/debian-lts-announce/2025/05/msg00045.htmlReference removed https://lists.debian.org/debian-lts-announce/2025/05/msg00030.html—Reference removed https://lists.debian.org/debian-lts-announce/2025/05/msg00045.html—Source identifier: af854a3a-2127-422b-91ae-364da2661108
Record modifiedSiemens ADP
Show 6 original changes
Individual changes of this event as published by NVD Type Action Before After Affected versions (publisher) added —Affected value modified. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2025/21xxx/CVE-2025-21862.json">CVE-2025-21862</a>Reference added —https://cert-portal.siemens.com/productcert/html/ssa-082556.htmlReference added —https://cert-portal.siemens.com/productcert/html/ssa-265688.htmlReference added —https://cert-portal.siemens.com/productcert/html/ssa-784472.htmlReference removed https://cert-portal.siemens.com/productcert/html/ssa-082556.html—Reference removed https://cert-portal.siemens.com/productcert/html/ssa-265688.html—Source identifier: 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e
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<a href="https://intel.neosec.eu/en/cve/CVE-2025-21862"><img src="https://intel.neosec.eu/badge/cve/CVE-2025-21862.svg?lang=en" alt="CVE-2025-21862 – NEOSEC Intel" height="20"></a>