CVE-2020-35509Network attack vector

Authenticated access via expired certificate

Published Aug 23, 2022 · Updated Jun 30, 2025

Improper certificate validation in Red Hat build of Keycloak 11.0.3 and 12.0.0 allows remote authenticated users to gain access via an expired certificate. The X.509 direct-grant authenticator omitted certificate timestamp validation, so an expired client certificate could be accepted during token issuance. Exploitation requires access to a configured direct-grant flow and trusted certificate identity, enabling unauthorized access to protected resources with confidentiality and integrity impact.

CVSS severity5.4
Medium
EPSS probability0.34%
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 Red Hat build of Keycloak 11.0.3 and 12.0.0 allows remote authenticated users to gain access via an expired certificate. The X.509 direct-grant authenticator omitted certificate timestamp validation, so an expired client certificate could be accepted during token issuance. Exploitation requires access to a configured direct-grant flow and trusted certificate identity, enabling unauthorized access to protected resources with confidentiality and integrity impact.

The record

CVE
CVE-2020-35509
Published
Aug 23, 2022
Updated
Jun 30, 2025
Vendor
Red Hat
Product
Red Hat build of Keycloak
Classifications
CWE-295, CWE-20, T1190
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Aug 23, 2022CVE publishedPublication date reported by the CVE source.
  2. Jun 30, 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=11.0.3, 12.0.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Red Hat · Red Hat build of Keycloakversion=11.0.3, 12.0.0

Published CVSS scores

5.4NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/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
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-295Improper Certificate Validation
CWE-20Improper Input Validation
T1190Exploit Public-Facing Application

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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