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Linux CVE-2025-39726

MEDIUM
Race Condition (CWE-362)
2025-09-05 416baaa9-dc9f-4396-8d5f-8c081fb06d67
Information Disclosure Linux Race Condition
4.7
CVSS 3.1 · NVD
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Vulnerability Assessment

Weakness
CWE
CWE-362
OWASP Top 10:2025
A06:2025 - Insecure Design
ASVS 5.0
V15 - Secure Coding and Architecture Concurrency control, locking
MITRE ATT&CK

1 technique across 1 tactic: Privilege Escalation

The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up.

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Impact

CVSS score of 4.7 (MEDIUM). Attack characteristics: local attack vector, high complexity, low privileges required, no user interaction not required. EPSS exploitation probability: 0.01%.
Exploit ScenarioDerived

Successful exploitation could compromise the medium-severity affected system.
This Month Plan within 30 days. Why: MEDIUM severity (CVSS 4.0-6.9).
Patch available 0.0% exploitation probability (EPSS)

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AnalysisAIv1 – Mar 28, 2026

In the Linux kernel, the following vulnerability has been resolved: s390/ism: fix concurrency management in ism_cmd() The s390x ISM device data sheet clearly states that only one request-response. Rated medium severity (CVSS 4.7).

RemediationAI

A vendor patch is available. Apply the latest security update as soon as possible. Apply vendor patches when available. Implement network segmentation and monitoring as interim mitigations.

Affects your stack

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Technical ContextAI · show details

This vulnerability is classified under CWE-362. In the Linux kernel, the following vulnerability has been resolved: s390/ism: fix concurrency management in ism_cmd() The s390x ISM device data sheet clearly states that only one request-response sequence is allowable per ISM function at any point in time. Unfortunately as of today the s390/ism driver in Linux does not honor that requirement. This patch aims to rectify that. This problem was discovered based on Aliaksei's bug report which states that for certain workloads the ISM functions end up entering error state (with PEC 2 as seen from the logs) after a while and as a consequence connections handled by the respective function break, and for future connection requests the ISM device is not considered -- given it is in a dysfunctional state. During further debugging PEC 3A was observed as well. A kernel message like [ 1211.244319] zpci: 061a:00:00.0: Event 0x2 reports an error for PCI function 0x61a is a reliable indicator of the stated function entering error state with PEC 2. Let me also point out that a kernel message like [ 1211.244325] zpci: 061a:00:00.0: The ism driver bound to the device does not support error recovery is a reliable indicator that the ISM function won't be auto-recovered because the ISM driver currently lacks support for it. On a technical level, without this synchronization, commands (inputs to the FW) may be partially or fully overwritten (corrupted) by another CPU trying to issue commands on the same function. There is hard evidence that this can lead to DMB token values being used as DMB IOVAs, leading to PEC 2 PCI events indicating invalid DMA. But this is only one of the failure modes imaginable. In theory even completely losing one command and executing another one twice and then trying to interpret the outputs as if the command we intended to execute was actually executed and not the other one is also possible. Frankly, I don't feel confident about providing an exhaustive list of possible consequences. Affected products include: Linux Linux Kernel.

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Severity by source

NVD PRIMARY 4.7 MEDIUM
AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H
SUSE MEDIUM
Red Hat 5.9 MEDIUM

Primary rating from NVD.

CVSS VectorNVD

Attack Vector
Local
Attack Complexity
High
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

Lifecycle Timeline

2
Patch released
Mar 28, 2026 - 19:10 nvd
Patch available
CVE Published
Sep 05, 2025 - 18:15 nvd
MEDIUM 4.7

DescriptionNVD

In the Linux kernel, the following vulnerability has been resolved:

s390/ism: fix concurrency management in ism_cmd()

The s390x ISM device data sheet clearly states that only one request-response sequence is allowable per ISM function at any point in time. Unfortunately as of today the s390/ism driver in Linux does not honor that requirement. This patch aims to rectify that.

This problem was discovered based on Aliaksei's bug report which states that for certain workloads the ISM functions end up entering error state (with PEC 2 as seen from the logs) after a while and as a consequence connections handled by the respective function break, and for future connection requests the ISM device is not considered -- given it is in a dysfunctional state. During further debugging PEC 3A was observed as well.

A kernel message like [ 1211.244319] zpci: 061a:00:00.0: Event 0x2 reports an error for PCI function 0x61a is a reliable indicator of the stated function entering error state with PEC 2. Let me also point out that a kernel message like [ 1211.244325] zpci: 061a:00:00.0: The ism driver bound to the device does not support error recovery is a reliable indicator that the ISM function won't be auto-recovered because the ISM driver currently lacks support for it.

On a technical level, without this synchronization, commands (inputs to the FW) may be partially or fully overwritten (corrupted) by another CPU trying to issue commands on the same function. There is hard evidence that this can lead to DMB token values being used as DMB IOVAs, leading to PEC 2 PCI events indicating invalid DMA. But this is only one of the failure modes imaginable. In theory even completely losing one command and executing another one twice and then trying to interpret the outputs as if the command we intended to execute was actually executed and not the other one is also possible. Frankly, I don't feel confident about providing an exhaustive list of possible consequences.

Executive ViewAI

Why It Matters

CVE-2025-39726 presents moderate security risk, a race condition vulnerability rated CVSS 4.7. Exploitation could compromise the security of affected deployments. A patch is available and should be applied during regular vulnerability management.

Business Impact: Low
Compensating Controls

Apply vendor patch. If patching is delayed: implement rate limiting and resource quotas.

Threat Intelligence Overview

EPSS Score
0.0%
Top 98% exploitable
Data Quality
4 sources
Confidence: Medium
NVD CVE.org EPSS Vendor VulDB

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue
Severity MEDIUM
CISA KEV No
Public POC No
EPSS 0.0%
Patch available Yes
Active threat No
Deciding rule
MEDIUM severity (CVSS 4.0-6.9)
What every action level means
Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.
Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.
This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.
This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.
Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived
Defer
Exploitation· derived
None
System Exposure· derived
Small
Automatable· derived
No
Human Impact
Low

Priority Score

24
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +24
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

Information Disclosure MEDIUM

Information disclosure occurs when an application unintentionally exposes sensitive data that aids attackers in reconnaissance or directly compromises security.

Race Condition MEDIUM

Race conditions occur when multiple concurrent requests exploit the brief time gap between checking a condition and acting upon it (TOCTOU - Time of Check, Time of Use).

Affected Products (CPE)NVD

cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:6.16:rc1:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:6.16:rc2:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:6.16:rc3:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:6.16:rc4:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:6.16:rc5:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:6.16:rc6:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:6.16:rc7:*:*:*:*:*:*

Same weakness CWE-362 – Race Condition

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CVE-2023-36884 HIGH POC
7.5
CVE-2016-5195 HIGH POC
7.0
CVE-2017-1000112 HIGH POC
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CVE-2014-0196 MEDIUM POC
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CVE-2014-0226 MEDIUM POC
6.8
CVE-2016-1757 HIGH POC
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CVE-2016-8655 HIGH POC
7.8
CVE-2025-39964 MEDIUM POC
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Same technique Information Disclosure

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CVE-2019-2725 CRITICAL POC
9.8
CVE-2021-34523 CRITICAL POC
9.0
CVE-2013-2251 CRITICAL POC
9.8
CVE-2017-5638 CRITICAL POC
9.8
CVE-2025-24813 CRITICAL POC
9.8
CVE-2025-68613 HIGH POC
8.8
CVE-2015-1701 HIGH POC
7.8
CVE-2017-0147 HIGH POC
7.5

Vendor StatusVendor

SUSE

Severity: Medium
Product Status
Container suse/sl-micro/6.0/base-os-container:2.1.3-7.57 Container suse/sl-micro/6.1/base-os-container:2.2.1-5.40 Image SL-Micro Image SL-Micro-Azure Image SL-Micro-BYOS-Azure Image SL-Micro-BYOS-EC2 Image SL-Micro-BYOS-GCE Image SL-Micro-EC2 Image SLE-Micro Image SLE-Micro-Azure Image SLE-Micro-BYOS Image SLE-Micro-BYOS-Azure Image SLE-Micro-BYOS-EC2 Image SLE-Micro-BYOS-GCE Image SLE-Micro-EC2 Image SLE-Micro-GCE Image SUSE-Multi-Linux-Manager-Proxy-BYOS-Azure Image SUSE-Multi-Linux-Manager-Proxy-BYOS-EC2 Image SUSE-Multi-Linux-Manager-Proxy-BYOS-GCE Image SUSE-Multi-Linux-Manager-Server-Azure-llc Image SUSE-Multi-Linux-Manager-Server-Azure-ltd Image SUSE-Multi-Linux-Manager-Server-BYOS-Azure Image SUSE-Multi-Linux-Manager-Server-BYOS-EC2 Image SUSE-Multi-Linux-Manager-Server-BYOS-GCE Image SUSE-Multi-Linux-Manager-Server-EC2-llc Image SUSE-Multi-Linux-Manager-Server-EC2-ltd Affected
Container suse/sl-micro/6.0/kvm-os-container:2.1.3-6.80 Container suse/sl-micro/6.1/kvm-os-container:2.2.1-5.41 Affected
Container suse/sl-micro/6.0/rt-os-container:2.1.3-7.95 Container suse/sl-micro/6.1/rt-os-container:2.2.1-5.34 Affected
Container suse/sle-micro-rancher/5.3:latest Container suse/sle-micro-rancher/5.4:5.4.4.5.72 Image SLES15-SP4-BYOS Image SLES15-SP4-BYOS-Azure Image SLES15-SP4-BYOS-EC2 Image SLES15-SP4-BYOS-GCE Image SLES15-SP4-CHOST-BYOS Image SLES15-SP4-CHOST-BYOS-Aliyun Image SLES15-SP4-CHOST-BYOS-Azure Image SLES15-SP4-CHOST-BYOS-EC2 Image SLES15-SP4-CHOST-BYOS-GCE Image SLES15-SP4-CHOST-BYOS-SAP-CCloud Image SLES15-SP4-HPC-BYOS Image SLES15-SP4-HPC-BYOS-Azure Image SLES15-SP4-HPC-BYOS-EC2 Image SLES15-SP4-HPC-BYOS-GCE Image SLES15-SP4-HPC-EC2 Image SLES15-SP4-HPC-GCE Image SLES15-SP4-Hardened-BYOS Image SLES15-SP4-Hardened-BYOS-Azure Image SLES15-SP4-Hardened-BYOS-EC2 Image SLES15-SP4-Hardened-BYOS-GCE Image SLES15-SP4-Manager-Proxy-4-3-BYOS Image SLES15-SP4-Manager-Proxy-4-3-BYOS-Azure Image SLES15-SP4-Manager-Proxy-4-3-BYOS-EC2 Image SLES15-SP4-Manager-Proxy-4-3-BYOS-GCE Image SLES15-SP4-Manager-Server-4-3-BYOS Image SLES15-SP4-Manager-Server-4-3-BYOS-Azure Image SLES15-SP4-Manager-Server-4-3-BYOS-EC2 Image SLES15-SP4-Manager-Server-4-3-BYOS-GCE Image SLES15-SP4-Micro-5-3 Image SLES15-SP4-Micro-5-3-BYOS Image SLES15-SP4-Micro-5-3-BYOS-Azure Image SLES15-SP4-Micro-5-3-BYOS-EC2 Image SLES15-SP4-Micro-5-3-BYOS-GCE Image SLES15-SP4-Micro-5-3-EC2 Image SLES15-SP4-Micro-5-4 Image SLES15-SP4-Micro-5-4-BYOS Image SLES15-SP4-Micro-5-4-BYOS-Azure Image SLES15-SP4-Micro-5-4-BYOS-EC2 Image SLES15-SP4-Micro-5-4-BYOS-GCE Image SLES15-SP4-Micro-5-4-EC2 Image SLES15-SP4-Micro-5-4-GCE Image SLES15-SP4-SAP Image SLES15-SP4-SAP-Azure Image SLES15-SP4-SAP-EC2 Image SLES15-SP4-SAP-GCE Image SLES15-SP4-SAPCAL Image SLES15-SP4-SAPCAL-Azure Image SLES15-SP4-SAPCAL-EC2 Image SLES15-SP4-SAPCAL-GCE Affected
Container suse/sle-micro/base-5.5:2.0.4-5.8.212 Image SLES15-SP5-BYOS-Azure Image SLES15-SP5-BYOS-EC2 Image SLES15-SP5-BYOS-GCE Image SLES15-SP5-CHOST-BYOS-Aliyun Image SLES15-SP5-CHOST-BYOS-Azure Image SLES15-SP5-CHOST-BYOS-EC2 Image SLES15-SP5-CHOST-BYOS-GCE Image SLES15-SP5-CHOST-BYOS-GDC Image SLES15-SP5-CHOST-BYOS-SAP-CCloud Image SLES15-SP5-EC2 Image SLES15-SP5-GCE Image SLES15-SP5-HPC-BYOS-Azure Image SLES15-SP5-HPC-BYOS-EC2 Image SLES15-SP5-HPC-BYOS-GCE Image SLES15-SP5-Hardened-BYOS-Azure Image SLES15-SP5-Hardened-BYOS-EC2 Image SLES15-SP5-Hardened-BYOS-GCE Image SLES15-SP5-Manager-Proxy-5-0-BYOS Image SLES15-SP5-Manager-Proxy-5-0-BYOS-Azure Image SLES15-SP5-Manager-Proxy-5-0-BYOS-EC2 Image SLES15-SP5-Manager-Proxy-5-0-BYOS-GCE Image SLES15-SP5-Manager-Server-5-0 Image SLES15-SP5-Manager-Server-5-0-Azure-llc Image SLES15-SP5-Manager-Server-5-0-Azure-ltd Image SLES15-SP5-Manager-Server-5-0-BYOS Image SLES15-SP5-Manager-Server-5-0-BYOS-Azure Image SLES15-SP5-Manager-Server-5-0-BYOS-EC2 Image SLES15-SP5-Manager-Server-5-0-BYOS-GCE Image SLES15-SP5-Manager-Server-5-0-EC2-llc Image SLES15-SP5-Manager-Server-5-0-EC2-ltd Image SLES15-SP5-Micro-5-5 Image SLES15-SP5-Micro-5-5-Azure Image SLES15-SP5-Micro-5-5-BYOS Image SLES15-SP5-Micro-5-5-BYOS-Azure Image SLES15-SP5-Micro-5-5-BYOS-EC2 Image SLES15-SP5-Micro-5-5-BYOS-GCE Image SLES15-SP5-Micro-5-5-EC2 Image SLES15-SP5-Micro-5-5-GCE Image SLES15-SP5-SAPCAL-Azure Image SLES15-SP5-SAPCAL-EC2 Image SLES15-SP5-SAPCAL-GCE Affected

References

Advisories & patches
PATCH https://git.kernel.org/stable/c/1194ad0d44d66b273a02a3a22882dc863a68d764 PATCH https://git.kernel.org/stable/c/897e8601b9cff1d054cdd53047f568b0e1995726 PATCH https://git.kernel.org/stable/c/faf44487dfc80817f178dc8de7a0b73f960d019b PATCH https://git.kernel.org/stable/c/fafaa4982bedb5532f5952000f714a3e63023f40 ADVISORY https://ubuntu.com/security/notices/USN-8126-1 ADVISORY https://vuldb.com/vuln/322952 ADVISORY https://www.suse.com/support/update/SUSE-SU-2025:03600/ ADVISORY https://www.suse.com/support/update/SUSE-SU-2025:03614/ ADVISORY https://www.suse.com/support/update/SUSE-SU-2025:03615/ ADVISORY https://www.suse.com/support/update/SUSE-SU-2025:03628/ ADVISORY https://www.suse.com/support/update/SUSE-SU-2025:03634/ ADVISORY https://www.suse.com/support/update/SUSE-SU-2025:20851/ ADVISORY https://www.suse.com/support/update/SUSE-SU-2025:20861/ ADVISORY https://www.suse.com/support/update/SUSE-SU-2025:20870/ ADVISORY https://www.suse.com/support/update/SUSE-SU-2025:20898/ ADVISORY https://www.suse.com/support/update/SUSE-SU-2025:20994/ ADVISORY https://www.suse.com/support/update/SUSE-SU-2025:20996/ ADVISORY https://www.suse.com/support/update/SUSE-SU-2025:21074/ ADVISORY https://www.suse.com/support/update/SUSE-SU-2025:21139/ ADVISORY https://www.suse.com/support/update/SUSE-SU-2025:21179/ ADVISORY https://www.suse.com/support/update/SUSE-SU-2025:3716/ ADVISORY https://www.suse.com/support/update/SUSE-SU-2025:3751/ ADVISORY https://www.suse.com/support/update/SUSE-SU-2025:3761/ ADVISORY https://www.suse.com/support/update/SUSE-SU-2025:4057/ ADVISORY https://www.suse.com/support/update/SUSE-SU-2025:4132/ ADVISORY https://www.suse.com/support/update/SUSE-SU-2025:4141/ ADVISORY https://www.suse.com/support/update/SUSE-SU-2026:20316/ ADVISORY https://www.suse.com/support/update/SUSE-SU-2026:20332/ ADVISORY https://www.suse.com/support/update/SUSE-SU-2026:20560/ REF https://git.kernel.org/stable/c/79536c83cf38c285709757c4026da4ae151223ae

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