Is CVE-2021-3856 in the CISA KEV catalog?

No. CVE-2021-3856 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2021-3856?

CVE-2021-3856 has a CVSS v3 base score of 4.3 (MEDIUM).

What is the EPSS score for CVE-2021-3856?

CVE-2021-3856 has an EPSS score of 0.90% (55th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2021-3856?

Upgrade keycloak to 15.1.0 or later.

CVE & CISA-KEV Catalog

CVE-2021-3856

MEDIUM

4.3

CVSS v3

NVD

Description

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.

CWE-552 CWE-22Path Traversal

How to fix

Remediation Available

keycloakNVD

Affected:< 15.1.0Fixed in:15.1.0CVE-2021-3856derived from NVD

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityLow

Privileges RequiredLow

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityLow

IntegrityNone

AvailabilityNone

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

Exploit Intelligence

0.90%probability of exploitation in 30 days

55thpercentile

Moderate risk: more likely to be exploited than 55% of all known CVEs.

References

Patch2

Vendor Advisory3

Related Vulnerabilities

Other CWE-552 vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2020-17519	High	7.5	98%	KEV	Fix
CVE-2025-11371	High	7.5	92%	KEV	Fix
CVE-2023-50164	Critical	9.8	81%	-	Fix
CVE-2016-3715	Medium	5.5	75%	KEV	Fix
CVE-2020-15175	High	7.4	71%	-	Fix
CVE-2021-39316	High	7.5	67%	-	-

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Markdown

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2024-11-21.