CVE-2021-3856: Files or Directories Accessible to External Parties

August 26, 2022 (updated July 10, 2023)

ClassLoaderTheme and ClasspathThemeResourceProviderFactory allows reading any file available as a resource to the classloader. By sending requests for theme resources with a relative path from an external HTTP client, the client will receive the content of random files if available.

References

access.redhat.com/security/cve/CVE-2021-3856
bugzilla.redhat.com/show_bug.cgi?id=2010164
github.com/keycloak/keycloak/commit/73f0474008e1bebd0733e62a22aceda9e5de6743
github.com/keycloak/keycloak/pull/8588
issues.redhat.com/browse/KEYCLOAK-19422
nvd.nist.gov/vuln/detail/CVE-2021-3856

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