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OpenSSL CVE-2025-9231

MEDIUM
Covert Timing Channel (CWE-385)
2025-09-30 openssl-security@openssl.org
Information Disclosure OpenSSL
6.5
CVSS 3.1 · Vendor: openssl
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Vulnerability Assessment

Weakness
CWE
CWE-385
OWASP Top 10:2025
A06:2021 - Vulnerable and Outdated Components
ASVS 5.0
V15 - Secure Coding and Architecture Covert timing channel
Impact

CVSS score of 6.5 (MEDIUM). Attack characteristics: network attack vector, low complexity, no privileges required, no user interaction not required. EPSS exploitation probability: 0.02%.
Exploit ScenarioDerived

This vulnerability can be exploited remotely over the network. 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

Issue summary: A timing side-channel which could potentially allow remote recovery of the private key exists in the SM2 algorithm implementation on 64 bit ARM platforms. Rated medium severity (CVSS 6.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.

RemediationAI

No vendor patch is available at time of analysis. Monitor vendor advisories for updates. Apply vendor patches when available. Implement network segmentation and monitoring as interim mitigations.

Affected ProductsAI

See vendor advisory for affected versions.

Affects your stack

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Technical ContextAI · show details

This vulnerability is classified under CWE-385. Issue summary: A timing side-channel which could potentially allow remote recovery of the private key exists in the SM2 algorithm implementation on 64 bit ARM platforms. Impact summary: A timing side-channel in SM2 signature computations on 64 bit ARM platforms could allow recovering the private key by an attacker.. While remote key recovery over a network was not attempted by the reporter, timing measurements revealed a timing signal which may allow such an attack. OpenSSL does not directly support certificates with SM2 keys in TLS, and so this CVE is not relevant in most TLS contexts. However, given that it is possible to add support for such certificates via a custom provider, coupled with the fact that in such a custom provider context the private key may be recoverable via remote timing measurements, we consider this to be a Moderate severity issue. The FIPS modules in 3.5, 3.4, 3.3, 3.2, 3.1 and 3.0 are not affected by this issue, as SM2 is not an approved algorithm.

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Severity by source

Vendor (openssl) PRIMARY 6.5 MEDIUM
AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:L
SUSE MEDIUM
Red Hat 5.9 MEDIUM

Primary rating from Vendor (openssl).

CVSS VectorVendor: openssl

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

Lifecycle Timeline

2
Patch released
Apr 09, 2026 - 14:30 nvd
Patch available
CVE Published
Sep 30, 2025 - 14:15 nvd
MEDIUM 6.5

DescriptionCVE.org

Issue summary: A timing side-channel which could potentially allow remote recovery of the private key exists in the SM2 algorithm implementation on 64 bit ARM platforms.

Impact summary: A timing side-channel in SM2 signature computations on 64 bit ARM platforms could allow recovering the private key by an attacker..

While remote key recovery over a network was not attempted by the reporter, timing measurements revealed a timing signal which may allow such an attack.

OpenSSL does not directly support certificates with SM2 keys in TLS, and so this CVE is not relevant in most TLS contexts. However, given that it is possible to add support for such certificates via a custom provider, coupled with the fact that in such a custom provider context the private key may be recoverable via remote timing measurements, we consider this to be a Moderate severity issue.

The FIPS modules in 3.5, 3.4, 3.3, 3.2, 3.1 and 3.0 are not affected by this issue, as SM2 is not an approved algorithm.

Executive ViewAI

Why It Matters

CVE-2025-9231 presents notable security risk rated CVSS 6.5. Exploitation could compromise the security of affected deployments. Organizations should apply vendor updates when available and monitor for exploitation.

Business Impact: Moderate
Compensating Controls

Apply vendor patch. If patching is delayed: restrict network access and enable monitoring.

Threat Intelligence Overview

EPSS Score
0.0%
Top 94% exploitable
Threat Intel
3
1 source
Data Quality
7 sources
Confidence: High
NVD CVE.org EPSS CISA Vendor GitHub 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 Yes
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

Exploitation· derived
None
System Exposure· derived
Open
Automatable· derived
Yes

Priority Score

42
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +32
PoC: 0
Weaponized: 0
Threat intel: +10
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.

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7.8
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7.5

Vendor StatusVendor

SUSE

Severity: Medium
Product Status
Container suse/sl-micro/6.0/baremetal-os-container:2.1.3-4.16 Container suse/sl-micro/6.0/kvm-os-container:2.1.3-4.17 Container suse/sl-micro/6.0/rt-os-container:2.1.3-5.17 Affected
Container suse/sl-micro/6.0/base-os-container:2.1.3-4.16 Image SL-Micro Affected
Container suse/sl-micro/6.1/base-os-container:2.2.0-4.34 Affected
Container suse/sles/16.0/toolbox:16.3-1.6 Affected
Image SL-Micro-Azure Image SL-Micro-BYOS-Azure Image SL-Micro-BYOS-EC2 Image SL-Micro-BYOS-GCE Image SL-Micro-EC2 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

Threat IntelligenceMISP

CISA Advisories
ICSA-26-134-10 ICSA-26-188-05 ICSA-26-202-04
Sources: CISA (public domain)

References

Advisories & patches
ADVISORY https://vuldb.com/vuln/326395 ADVISORY https://www.suse.com/support/update/SUSE-SU-2025:21213/ ADVISORY https://www.suse.com/support/update/SUSE-SU-2025:21224/ ADVISORY https://www.suse.com/support/update/SUSE-SU-2026:20418/ REF http://www.openwall.com/lists/oss-security/2025/09/30/5 REF http://www.openwall.com/lists/oss-security/2026/05/11/11 REF https://cert-portal.siemens.com/productcert/html/ssa-032379.html REF https://cert-portal.siemens.com/productcert/html/ssa-089022.html REF https://cert-portal.siemens.com/productcert/html/ssa-253495.html REF https://cert-portal.siemens.com/productcert/html/ssa-585531.html REF https://github.com/openssl/openssl/commit/567f64386e43683888212226824b6a179885a0fe REF https://github.com/openssl/openssl/commit/cba616c26ac8e7b37de5e77762e505ba5ca51698 REF https://github.com/openssl/openssl/commit/eed5adc9f969d77c94f213767acbb41ff923b6f4 REF https://github.com/openssl/openssl/commit/fc47a2ec078912b3e914fab5734535e76c4820c2 REF https://openssl-library.org/news/secadv/20250930.txt

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