How severe is CVE-2020-35509?

CVE-2020-35509 has a CVSS score of 5.4/10, rated MEDIUM. Review your exposure and patch according to your risk tolerance.

Which packages are affected by CVE-2020-35509?

CVE-2020-35509 affects the following packages: org.keycloak:keycloak-core (Maven). Ecosystems affected: Maven.

How do I fix CVE-2020-35509?

Update org.keycloak:keycloak-core to 14.0.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2020-35509 is resolved across your whole dependency graph.

How do I detect CVE-2020-35509 in my Maven dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for org.keycloak:keycloak-core, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2020-35509 if there is no patch (or I can't update yet)?

If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Is CVE-2020-35509 actively exploited in the wild?

No public exploit code has been indexed for CVE-2020-35509 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2020-35509?

CVE-2020-35509 has an EPSS (Exploit Prediction Scoring System) score of 0.4%, placing it in the 29th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2020-35509?

CVE-2020-35509 is classified as Improper Input Validation (CWE-20), CWE-295 (CWE-295). These weakness types describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2020-35509 published, and has it been updated?

CVE-2020-35509 was published on August 23, 2022 and was last updated on October 24, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

☕

☕ Maven

Not in CISA KEV

MEDIUM severity

CVE-2020-35509 — keycloak-core

MEDIUMFix: keycloak/keycloak#6330

CVE-2020-35509 is a medium-severity (CVSS 5.4) Improper Input Validation vulnerability in org.keycloak:keycloak-core. A fix is available for org.keycloak:keycloak-core — see the affected versions and patch details below.

Keycloak vulnerable to Improper Certificate Validation

Also known asGHSA-rpj2-w6fr-79hc

Published

Aug 23, 2022

Updated

Oct 24, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Exploitation data as of Nov 6, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for CVE-2020-35509.

EPSS Exploitation Probability

via FIRST.org ↗

0.4%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs29th percentile — riskier than 29% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

1 pkg affected

☕org.keycloak:keycloak-core

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Maven packages — download data is not available via public APIs for these ecosystems.

Description

This issue was partially fixed in version 13.0.1 and more completely fixed in version 14.0.0.

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
☕Maven	`org.keycloak:keycloak-core`	all versions	14.0.0`org.keycloak:keycloak-core:14.0.0`

Affected Products

1 product · 2 configurations

Application

keycloakredhat

2 versions

11.0.312.0.0

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for org.keycloak:keycloak-core, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update org.keycloak:keycloak-core to 14.0.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2020-35509 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Fixing This On Your OS

If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.

Red HatLow

Product	Fixed in	Advisory
Red Hat Single Sign-On 7.4.9	see advisory	RHSA-2021:3534
Red Hat Single Sign-On 7.4 for RHEL 6	`rh-sso7-keycloak-0:9.0.15-1.redhat_00002.1.el6sso`	RHSA-2021:3527
Red Hat Single Sign-On 7.4 for RHEL 7	`rh-sso7-keycloak-0:9.0.15-1.redhat_00002.1.el7sso`	RHSA-2021:3528
Red Hat Single Sign-On 7.4 for RHEL 8	`rh-sso7-keycloak-0:9.0.15-1.redhat_00002.1.el8sso`	RHSA-2021:3529

Frequently Asked Questions

keycloak accepts an expired certificate by the direct-grant authenticator because of missing time stamp validations. The highest threat from this vulnerability is to data confidentiality and integrity. This issue was partially fixed in version [13.0.1](https://github.com/keycloak/keycloak/pull/6330) and more completely fixed in version [14.0.0](https://github.com/keycloak/keycloak/pull/8067).

O3 Security · Impact-Aware SCA

Is CVE-2020-35509 in your dependencies?

Find it across Maven, including transitive dependencies.

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CVSS Score

5.4/10CVSS v3 base

Vector breakdown

Attack Vector

Network

Attack Complexity

Low

Privileges Required

Low

User Interaction

None

Scope

Unchanged

Confidentiality

Low

Integrity

Low

Availability

None

Raw vector

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N

CWE Classification

CWE-20Improper Input Validation CWE-295CWE-295

Weaponization

No Nuclei template, Metasploit module or public proof-of-concept found.

OpenSSF Scorecard

Package health score

keycloak

9.3/10

Code-Review10/10

Maintained10/10

Branch-Protection8/10

Assessed Nov 2, 2026

Timeline

Disclosed

Aug 23, 2022

Last updated

Oct 24, 2026

Identifiers

CVE-2020-35509

GHSA-rpj2-w6fr-79hc

References

Advisoryaccess.redhat.com · cve 2020 35509 Advisorynvd.nist.gov · CVE 2020 35509 Webgithub.com Webgithub.com Webgithub.com · 478319348bdfdb9b6d39122f41edf2af79f679bb Webbugzilla.redhat.com · show bug.cgi Webgithub.com · ValidateX509CertificateUsername.java Packagegithub.com · keycloak

Related vulnerabilities

This CVE is medium severity; 7 of 8 other CVEs affecting keycloak-core are rated as high or higher (top: high).

CVE-2024-4028CVE-2024-10039CVE-2024-7318CVE-2023-6841CVE-2024-7260CVE-2023-6927CVE-2023-4918CVE-2023-0105

Provenance

Sources

OSV.devNVDFIRST.org (EPSS)

Last verifiedOct 24, 2026