CVE-2025-21726

Kernel memory corruption via padata use-after-free

Published Feb 27, 2025 · Updated Aug 5, 2026

Use-after-free in Linux kernel padata allows local users to access freed kernel memory through concurrent crypto request processing. padata_reorder queues reorder_work on serial_wq without retaining a reference to its parallel_data object, so crypto_del_alg can free the object before invoke_padata_reorder uses it. Low-privileged local access and a race between serialized crypto requests and algorithm deletion are required; successful exploitation corrupts kernel memory and crashes the system.

CVSS severity7.8
High
EPSS probability0.23%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Use-after-free in Linux kernel padata allows local users to access freed kernel memory through concurrent crypto request processing. padata_reorder queues reorder_work on serial_wq without retaining a reference to its parallel_data object, so crypto_del_alg can free the object before invoke_padata_reorder uses it. Low-privileged local access and a race between serialized crypto requests and algorithm deletion are required; successful exploitation corrupts kernel memory and crashes the system.

The record

CVE
CVE-2025-21726
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

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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=5.4.19 <5.5; version=5.5.3 <5.6; version=5.6; version=b4c8ed0bf977760a206997b6429a7ac91978f440; version=bbefa1dd6a6d53537c11624752219e39959d04fb <4c6209efea2208597dbd3e52dc87a0d1a8f2dbe1; version=bbefa1dd6a6d53537c11624752219e39959d04fb <6f45ef616775b0ce7889b0f6077fc8d681ab30bc; version=bbefa1dd6a6d53537c11624752219e39959d04fb <7000507bb0d2ceb545c0a690e0c707c897d102c2; version=bbefa1dd6a6d53537c11624752219e39959d04fb <8ca38d0ca8c3d30dd18d311f1a7ec5cb56972cac; version=bbefa1dd6a6d53537c11624752219e39959d04fb <a54091c24220a4cd847d5b4f36d678edacddbaf0; version=bbefa1dd6a6d53537c11624752219e39959d04fb <dd7d37ccf6b11f3d95e797ebe4e9e886d0332600; version=bbefa1dd6a6d53537c11624752219e39959d04fb <f4f1b1169fc3694f9bc3e28c6c68dbbf4cc744c0; version=e43d65719527043f1ef79ecba9d4ede58cbc7ffe

Published CVSS scores

7.8CISA-ADPCVSS: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.

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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
T1068Exploitation for Privilege Escalation

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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