CVE-2021-4314Network attack vector

Unauthenticated impersonation via manipulated JWT validation

Published Jan 18, 2023 · Updated Apr 3, 2025

Improper authentication in Open Mainframe Project Zowe 1.16.0 through 1.18.x allows remote attackers to impersonate any user via a JWT. The API Mediation Layer or ZAAS client treats attacker-manipulated JWT claims as valid without the JWT secret when the connected z/OSMF lacks APAR PH12143. The flaw is reachable without credentials only in that deployment state and lets a forged identity reach southbound services, with no reported confidentiality or availability impact.

CVSS severity5.3
Medium
EPSS probability0.44%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper authentication in Open Mainframe Project Zowe 1.16.0 through 1.18.x allows remote attackers to impersonate any user via a JWT. The API Mediation Layer or ZAAS client treats attacker-manipulated JWT claims as valid without the JWT secret when the connected z/OSMF lacks APAR PH12143. The flaw is reachable without credentials only in that deployment state and lets a forged identity reach southbound services, with no reported confidentiality or availability impact.

The record

CVE
CVE-2021-4314
Published
Jan 18, 2023
Updated
Apr 3, 2025
Vendor
Open Mainframe Project
Product
Zowe
Classifications
CWE-287, CWE-269, T1606
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jan 18, 2023CVE publishedPublication date reported by the CVE source.
  2. Apr 3, 2025Record 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=1.16.0 <1.19.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Open Mainframe Project · Zoweversion=1.16.0 <1.19.0

Published CVSS scores

5.3CISA ADPCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

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 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-287Improper Authentication
CWE-269Improper Privilege Management
T1606Forge Web Credentials

Public exploit references

No public exploit references are available in this record.

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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