Is CVE-2021-43859 in the CISA KEV catalog?

No. CVE-2021-43859 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2021-43859?

CVE-2021-43859 has a CVSS v3 base score of 7.5 (HIGH).

What is the EPSS score for CVE-2021-43859?

CVE-2021-43859 has an EPSS score of 7.93% (94th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2021-43859?

Upgrade libxstream-java on debian 11 to 1.4.15-3+deb11u3 or later.

CVE & CISA-KEV Catalog

CVE-2021-43859

HIGHEPSS 94th pctl

7.5

CVSS v3

NVD

Description

XStream is an open source java library to serialize objects to XML and back again. Versions prior to 1.4.19 may allow a remote attacker to allocate 100% CPU time on the target system depending on CPU type or parallel execution of such a payload resulting in a denial of service only by manipulating the processed input stream. XStream 1.4.19 monitors and accumulates the time it takes to add elements to collections and throws an exception if a set threshold is exceeded. Users are advised to upgrade as soon as possible. Users unable to upgrade may set the NO_REFERENCE mode to prevent recursion. See GHSA-rmr5-cpv2-vgjf for further details on a workaround if an upgrade is not possible.

CWE-400Resource Exhaustion

How to fix

Remediation Available

libxstream-javaDebian

Fixed in:1.4.15-3+deb11u3CVE-2021-43859

Fixed in:1.4.19-1CVE-2021-43859

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 RequiredNone

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityNone

IntegrityNone

AvailabilityHigh

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

Exploit Intelligence

7.93%probability of exploitation in 30 days

94thpercentile

High risk: more likely to be exploited than 94% of all known CVEs.

References

Patch3

Exploit2

Third-Party Advisory2

Mailing List2

Other references1

lists.debian.org

Related Vulnerabilities

Other CWE-400 (Resource Exhaustion) vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2023-44487	High	7.5	100%	KEV	Fix
CVE-2021-44228	Critical	10.0	100%	KEV + Ransom	Fix
CVE-2011-3192	High	7.8	99%	-	Fix
CVE-2019-11478	Medium	5.3	95%	-	Fix
CVE-2024-25617	Medium	5.3	89%	-	Fix
CVE-2018-1000115	High	7.5	89%	-	Fix

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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 2025-11-03.