CVE-2026-56451Network attack vector

Authentication bypass via unchecked JWT algorithm

Published Jul 14, 2026 · Updated Jul 14, 2026

Improper JWT verification in Siemens Opcenter X before V2604 allows remote attackers to impersonate any user and bypass authentication. The token-validation logic accepts the algorithm declared in an attacker-supplied JWT header without properly validating it, enabling forged tokens. No account or user interaction is required; a forged token can assume an administrative identity and grant full unauthorized application access.

CVSS severity10.0
Critical
EPSS probability0.50%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper JWT verification in Siemens Opcenter X before V2604 allows remote attackers to impersonate any user and bypass authentication. The token-validation logic accepts the algorithm declared in an attacker-supplied JWT header without properly validating it, enabling forged tokens. No account or user interaction is required; a forged token can assume an administrative identity and grant full unauthorized application access.

The record

CVE
CVE-2026-56451
Published
Jul 14, 2026
Updated
Jul 14, 2026
Vendor
Siemens
Product
Opcenter X
Classifications
CWE-347, T1550.001
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 14, 2026CVE publishedPublication date reported by the CVE source.
  2. Jul 14, 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 <V2604

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Siemens · Opcenter Xversion=0 <V2604

Published CVSS scores

10.0Siemens ProductCERTCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:L/SC:L/SI:H/SA:H
10.0Siemens ProductCERTCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/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 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 exploitUnconfirmed

Weakness, pattern, technique

CWE-347Improper Verification of Cryptographic Signature
T1550.001Use Alternate Authentication Material: Application Access Token

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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