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HIGH severity

CVE-2021-20202 — keycloak-core

HIGH

CVE-2021-20202 is a high-severity (CVSS 7.3) CWE-377 vulnerability in org.keycloak:keycloak-core. A fix is available for org.keycloak:keycloak-core — see the affected versions and patch details below.

Temporary Directory Hijacking Vulnerability in Keycloak

Also known asGHSA-6xp6-fmc8-pmmr
Published
Updated
Affected
1 pkg
Patched
1 / 1
Exploits
None indexed
Exploitation data as of Nov 9, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗
0.3%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs23th percentile — riskier than 23% of all scored CVEsHighest risk
0.00%0.27%0.53%0.80%0.0%0.3%May 26Sep 26Nov 26

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

A flaw was found in keycloak. Directories can be created prior to the Java process creating them in the temporary directory, but with wider user permissions, allowing the attacker to have access to the contents that keycloak stores in this directory. The highest threat from this vulnerability is to data confidentiality and integrity.

Affected Packages

1 total 1 fixed
EcosystemPackageVulnerable rangeFix
☕Mavenorg.keycloak:keycloak-coreall versions13.0.0org.keycloak:keycloak-core:13.0.0

Affected Products

1 product · 1 configurations
Application
keycloakredhat
< 13.0.0
range

Detection & mitigation playbook

Open-source dependency

  1. 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.

  2. Fix

    Update org.keycloak:keycloak-core to 13.0.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-20202 is resolved across your whole dependency graph.

  3. 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 HatModerate
Workaround published by Red Hat
By switching to the `Files` API, you are allowed to exclusively set the file permissions when creating directories or creating temporary directories.
Source: Red Hat security advisory for CVE-2021-20202 (CC BY 4.0)

Frequently Asked Questions

A flaw was found in keycloak. Directories can be created prior to the Java process creating them in the temporary directory, but with wider user permissions, allowing the attacker to have access to the contents that keycloak stores in this directory. The highest threat from this vulnerability is to data confidentiality and integrity.
O3 Security · Impact-Aware SCA

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CVE-2021-20202: keycloak-core — Fixed in 13.0.0