CVE-2025-21762

Service interruption via unprotected arp_xmit state access

Published Feb 27, 2025 · Updated Aug 5, 2026

Use-after-free in arp_xmit in Linux 4.4 and later allows attackers to interrupt service through concurrent ARP packet transmission. The function reads network-device state without holding RTNL or entering an RCU read-side critical section, so that state can be freed concurrently. Published assessments differ: Linux identifies a high-complexity network path, while Siemens requires low-privileged local access and reports availability loss only.

CVSS severity8.1
High
EPSS probability0.62%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Use-after-free in arp_xmit in Linux 4.4 and later allows attackers to interrupt service through concurrent ARP packet transmission. The function reads network-device state without holding RTNL or entering an RCU read-side critical section, so that state can be freed concurrently. Published assessments differ: Linux identifies a high-complexity network path, while Siemens requires low-privileged local access and reports availability loss only.

The record

CVE
CVE-2025-21762
Published
Feb 27, 2025
Updated
Aug 5, 2026
Vendor
Siemens
Product
SIMATIC S7-1500 TM MFP - GNU/Linux subsystem
Classifications
CWE-416, CWE-20, T1499
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Feb 27, 2025CVE publishedPublication date reported by the CVE source.
  2. Aug 5, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0 <*

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

Siemens · SIMATIC S7-1500 TM MFP - GNU/Linux subsystemversion=0 <*
The Linux Kernel Organization · Linuxversion=29a26a56803855a79dbd028cd61abee56237d6e5 <01d1b5c9abcaff29a43f1d17a19c33eec92c7dbe; version=29a26a56803855a79dbd028cd61abee56237d6e5 <10f555e3f573d004ae9d89b3276abb58c4ede5c3; version=29a26a56803855a79dbd028cd61abee56237d6e5 <2c331718d3389b6c5f6855078ab7171849e016bd; version=29a26a56803855a79dbd028cd61abee56237d6e5 <307cd1e2d3cb1cbc6c40c679cada6d7168b18431; version=29a26a56803855a79dbd028cd61abee56237d6e5 <a42b69f692165ec39db42d595f4f65a4c8f42e44; version=29a26a56803855a79dbd028cd61abee56237d6e5 <d9366ac2f956a1948b68c0500f84a3462ff2ed8a; version=29a26a56803855a79dbd028cd61abee56237d6e5 <e9f4dee534eb1b225b0a120395ad9bc2afe164d3; version=29a26a56803855a79dbd028cd61abee56237d6e5 <f189654459423d4d48bef2d120b4bfba559e6039; version=4.4
Siemens · SIMATIC S7-1500 TM MFP - BIOSversion=0 <*

Published CVSS scores

5.5Siemens ProductCERTCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
8.1Linux CNACVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
7.8CISA ADPCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
7.1OracleCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-416Use After Free
CWE-20Improper Input Validation
T1499Endpoint Denial of Service

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo