HOMEVULNERABILITIESCVE-2021-43859
HIGH

CVE-2021-43859

CWE-400Published: February 1, 2022· Updated: Jun 17, 2026

7.5
CVSS v3.1

Official 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.

NVD Source

Technical Analysis

CVE-2021-43859 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.

The vulnerability requires no privileges and no user interaction, making it a prime target for automated exploitation campaigns and worm-like propagation.

A successful exploit results in availability disruption (denial of service), with a CVSS base score of 7.5.

CVSS v3.1 Vector Breakdown

Exploitability
Attack VectorNetwork
Attack ComplexityLow
Privileges Req.None
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

Affected Vendors & Products

Debian1 product(s)
debian linux
Fedora1 product(s)
fedora
jenkins1 product(s)
jenkins
Oracle7 product(s)
commerce guided searchcommunications brm - elastic charging enginecommunications cloud native core automated test suitecommunications diameter intelligence hubcommunications policy managementflexcube private bankingretail xstore point of service
xstream1 product(s)
xstream
Source: NVD CPE · 17 total CPE entries

Exploit & PoC Resources

NO KNOWN EXPLOITNo public exploit confirmed at this time
Exploit-DB
Offensive Security exploit database
GitHub PoC Search
Community PoC repositories
Rapid7 / Metasploit
Metasploit module search
PacketStorm
Security advisories & exploits
NVD Detail
Official NIST entry
MITRE CVE
CVE Program entry
External links open in a new tab. Always verify in a controlled environment before use.

Official Patches & Advisories

PATCHhttps://github.com/x-stream/xstream/commit/e8e88621ba1c85ac3b8620337dd672e0c0c3a846
PATCHhttps://www.oracle.com/security-alerts/cpuapr2022.html
PATCHhttps://www.oracle.com/security-alerts/cpujul2022.html
PATCHhttps://github.com/x-stream/xstream/commit/e8e88621ba1c85ac3b8620337dd672e0c0c3a846
PATCHhttps://www.oracle.com/security-alerts/cpuapr2022.html
PATCHhttps://www.oracle.com/security-alerts/cpujul2022.html
ADVISORYhttp://www.openwall.com/lists/oss-security/2022/02/09/1
ADVISORYhttps://github.com/x-stream/xstream/security/advisories/GHSA-rmr5-cpv2-vgjf
ADVISORYhttps://lists.debian.org/debian-lts-announce/2022/02/msg00018.html
ADVISORYhttps://x-stream.github.io/CVE-2021-43859.html
ADVISORYhttp://www.openwall.com/lists/oss-security/2022/02/09/1
ADVISORYhttps://github.com/x-stream/xstream/security/advisories/GHSA-rmr5-cpv2-vgjf
ADVISORYhttps://lists.debian.org/debian-lts-announce/2022/02/msg00018.html
ADVISORYhttps://x-stream.github.io/CVE-2021-43859.html

All References (19)

→
http://www.openwall.com/lists/oss-security/2022/02/09/1Mailing List · Third Party Advisory
→
https://github.com/x-stream/xstream/commit/e8e88621ba1c85ac3b8620337dd672e0c0c3a846Patch · Third Party Advisory
→
https://github.com/x-stream/xstream/security/advisories/GHSA-rmr5-cpv2-vgjfExploit · Third Party Advisory
→
https://lists.debian.org/debian-lts-announce/2022/02/msg00018.htmlMailing List · Third Party Advisory
→
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/VACQYG356OHUTD5WQGAQ4L2TTFTAV3SJ/Mailing List
→
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/XODFRE2ZL64FICBJDOPWOLPTSSAI4U7X/Mailing List
→
https://www.oracle.com/security-alerts/cpuapr2022.htmlPatch · Third Party Advisory
→
https://www.oracle.com/security-alerts/cpujul2022.htmlPatch · Third Party Advisory
→
https://x-stream.github.io/CVE-2021-43859.htmlExploit · Vendor Advisory
→
http://www.openwall.com/lists/oss-security/2022/02/09/1Mailing List · Third Party Advisory
→
https://github.com/x-stream/xstream/commit/e8e88621ba1c85ac3b8620337dd672e0c0c3a846Patch · Third Party Advisory
→
https://github.com/x-stream/xstream/security/advisories/GHSA-rmr5-cpv2-vgjfExploit · Third Party Advisory
→
https://lists.debian.org/debian-lts-announce/2022/02/msg00018.htmlMailing List · Third Party Advisory
→
https://lists.debian.org/debian-lts-announce/2024/12/msg00023.html
→
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/VACQYG356OHUTD5WQGAQ4L2TTFTAV3SJ/Mailing List

Quick Facts

CVE IDCVE-2021-43859
CVSS Score7.5 / 10
SeverityHIGH
WeaknessCWE-400
CISA KEVNo
Affected5 vendor(s)
PublishedFeb 1, 2022

Related CVEs (CWE-400)

CVE-2018-19282
9.8
CVE-2018-11936
9.8
CVE-2025-43193
9.8
CVE-2017-1000378
9.8
CVE-2025-61303
9.8
CVE-2013-20004
9.8

Recommended Actions

  • →Apply vendor patches immediately
  • →Monitor CVE-2021-43859 in threat intel feeds
  • →Review IDS/IPS signatures for exploitation attempts
Data sourced from NVD (NIST), CISA KEV, and EPSS (FIRST). Analysis generated by CTIWatch. CVE data is provided under the NVD usage policy.
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