CVE-2026-9758Public exploitNetwork attack vector

Authentication bypass via subject-length certificate comparison

Published Jun 10, 2026 · Updated Jun 10, 2026

Improper certificate validation in Systerel S2OPC 1.5.0 through 1.7.2 allows remote attackers to establish trusted OPC UA connections. The MbedTLS and CycloneCrypto wrappers compare raw certificate bytes using the subject-name length rather than the full certificate length. Exploitation requires a well-formed certificate that passes every other validation step and matches a trusted entry's subject and total length, causing an untrusted peer to be accepted as trusted.

CVSS severity7.3
High
EPSS probability0.12%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper certificate validation in Systerel S2OPC 1.5.0 through 1.7.2 allows remote attackers to establish trusted OPC UA connections. The MbedTLS and CycloneCrypto wrappers compare raw certificate bytes using the subject-name length rather than the full certificate length. Exploitation requires a well-formed certificate that passes every other validation step and matches a trusted entry's subject and total length, causing an untrusted peer to be accepted as trusted.

The record

CVE
CVE-2026-9758
Published
Jun 10, 2026
Updated
Jun 10, 2026
Vendor
Systerel
Product
S2OPC
Classifications
CWE-295, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jun 10, 2026CVE publishedPublication date reported by the CVE source.
  2. Jun 10, 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=1.5.0 <1.7.3

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Systerel · S2OPCversion=1.5.0 <1.7.3

Published CVSS scores

7.3GitLab Inc.CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L

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)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-295Improper Certificate Validation
T1190Exploit Public-Facing Application

Public exploit references

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

Technologies

Your stack

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Your stack

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