CVE-2025-21727

Local privilege escalation via padata teardown race

Published Feb 27, 2025 · Updated Aug 5, 2026

Use-after-free in Linux 5.4 through 6.13.1 and the SIMATIC S7-1500 TM MFP GNU/Linux subsystem allows local users to gain privileges. When padata_reorder loops as a crypto algorithm is deleted, the shell reference count can reach zero before padata_find_next reads the freed parallel_data object. An unprivileged local user can drive both sides through AF_ALG and crypto teardown, enabling kernel-memory access, control-flow hijack, or a kernel panic.

CVSS severity7.8
High
EPSS probability0.22%
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 Linux 5.4 through 6.13.1 and the SIMATIC S7-1500 TM MFP GNU/Linux subsystem allows local users to gain privileges. When padata_reorder loops as a crypto algorithm is deleted, the shell reference count can reach zero before padata_find_next reads the freed parallel_data object. An unprivileged local user can drive both sides through AF_ALG and crypto teardown, enabling kernel-memory access, control-flow hijack, or a kernel panic.

The record

CVE
CVE-2025-21727
Published
Feb 27, 2025
Updated
Aug 5, 2026
Vendor
Siemens
Product
SIMATIC S7-1500 TM MFP - GNU/Linux subsystem
Classifications
CWE-416, T1068
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=5.4; version=b128a30409356df65f1a51cff3eb986cac8cfedc <0ae2f332cfd2d74cf3ce344ec9938cf3e29c3ccd; version=b128a30409356df65f1a51cff3eb986cac8cfedc <573ac9c70bf7885dc85d82fa44550581bfc3b738; version=b128a30409356df65f1a51cff3eb986cac8cfedc <80231f069240d52e98b6a317456c67b2eafd0781; version=b128a30409356df65f1a51cff3eb986cac8cfedc <bbccae982e9fa1d7abcb23a5ec81cb0ec883f7de; version=b128a30409356df65f1a51cff3eb986cac8cfedc <e01780ea4661172734118d2a5f41bc9720765668; version=b128a30409356df65f1a51cff3eb986cac8cfedc <f3e0b9f790f8e8065d59e67b565a83154d9f3079; version=b128a30409356df65f1a51cff3eb986cac8cfedc <f78170bee51469734b1a306a74fc5f777bb22ba6

Published CVSS scores

7.8Siemens ProductCERTCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
7.8Linux kernel CVE teamCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/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 10, 2026Sep 16, 2026
Latest reporting daySep 16, 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
T1068Exploitation for Privilege Escalation

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