CVE-2021-43859 | Denial of Service by injecting highly recursive collections or maps in XStream

Exp

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.

Published: 2022-02-01 Last update: 2025-11-03 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2021-43859 is rated High Exploit Risk (74.6/100): CVSS High severity, with medium exploitation likelihood (EPSS 1.94%). 2 public exploit reference(s) are indexed (Exploit-DB). Public exploits are available—assess exposure, apply mitigations, and prioritize patching.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Public exploit references (Exploit-DB) for CVE-2021-43859

EDB-ID Source Kind Published Link
— nvd_ref exploit_tag Exploit-DB ↗
— nvd_ref exploit_tag Exploit-DB ↗

Exploit prediction scoring system (EPSS) score for CVE-2021-43859

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2025-12-28 1.34% 1.94% +0.60%
2 2025-12-27 1.94% 1.34% -0.60%
3 2025-12-13 — 1.94% —

Full EPSS history (36 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2021-43859

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
7.5 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 3.6 [email protected]
7.5 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 3.6 [email protected]
5.0 2.0 MEDIUM
AV:N/AC:L/Au:N/C:N/I:N/A:P Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:L)
Exploitation conditions are straightforward and predictable.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:N)
No confidentiality impact.
Integrity impact (I:N)
No integrity impact.
Availability impact (A:P)
Partial availability impact.
 10.0 2.9 [email protected]

Weakness enumeration for CVE-2021-43859

GitHub Security Advisory for CVE-2021-43859

GHSA-rmr5-cpv2-vgjf · Severity: high · Ecosystem: maven — Denial of Service by injecting highly recursive collections or maps in XStream

OS Trackers for CVE-2021-43859

vendor priority summary link
debian not yet assigned CVE-2021-43859 not yet assigned priority: Debian including 1 source packages (libxstream-java), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. https://security-tracker.debian.org/tracker/CVE-2021-43859
redhat medium — https://access.redhat.com/security/cve/CVE-2021-43859
suse medium CVE-2021-43859 severity moderate: SUSE including 241 source package names (5.0.0-beta1.2.122:xstream-1.4.19-3.18.2, 5.1.0.6.40:xstream-1.4.19-3.18.2, …), 274 product×package rows across 30 product lines (Container suse/manager/5.0/x86_64/server, Container suse/multi-linux-manager/5.1/x86_64/server, … (30 product lines)): Known Affected 231, Fixed 43. https://www.suse.com/security/cve/CVE-2021-43859/
ubuntu medium CVE-2021-43859 medium priority: Ubuntu including 1 source packages (libxstream-java), 14 status rows across 14 suites (bionic, focal, impish, jammy, kinetic, lunar, mantic, noble, oracular, plucky, questing, trusty, upstream, xenial): needs-triage 8, ignored 6. https://ubuntu.com/security/CVE-2021-43859

Affected software / configurations for CVE-2021-43859

Vendor Product Version Raw CPE
jenkins jenkins < 2.319.3 cpe:2.3:a:jenkins:jenkins:*:*:*:*:*:*:*:*
jenkins jenkins >= 2.321, < 2.334 cpe:2.3:a:jenkins:jenkins:*:*:*:*:*:*:*:*
xstream xstream < 1.4.19 cpe:2.3:a:xstream:xstream:*:*:*:*:*:*:*:*
fedoraproject fedora 34 cpe:2.3:o:fedoraproject:fedora:34:*:*:*:*:*:*:*
fedoraproject fedora 35 cpe:2.3:o:fedoraproject:fedora:35:*:*:*:*:*:*:*
debian debian_linux 9.0 cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*
oracle commerce_guided_search 11.3.2 cpe:2.3:a:oracle:commerce_guided_search:11.3.2:*:*:*:*:*:*:*
oracle communications_brm_-_elastic_charging_engine < 12.0.0.4.6 cpe:2.3:a:oracle:communications_brm_-_elastic_charging_engine:*:*:*:*:*:*:*:*
oracle communications_brm_-_elastic_charging_engine 12.0.0.5.0 cpe:2.3:a:oracle:communications_brm_-_elastic_charging_engine:12.0.0.5.0:*:*:*:*:*:*:*
oracle communications_cloud_native_core_automated_test_suite 1.9.0 cpe:2.3:a:oracle:communications_cloud_native_core_automated_test_suite:1.9.0:*:*:*:*:*:*:*
oracle communications_diameter_intelligence_hub >= 8.0.0, <= 8.1.0 cpe:2.3:a:oracle:communications_diameter_intelligence_hub:*:*:*:*:*:*:*:*
oracle communications_diameter_intelligence_hub >= 8.2.0, <= 8.2.6 cpe:2.3:a:oracle:communications_diameter_intelligence_hub:*:*:*:*:*:*:*:*
oracle communications_policy_management 12.6.0.0.0 cpe:2.3:a:oracle:communications_policy_management:12.6.0.0.0:*:*:*:*:*:*:*
oracle flexcube_private_banking 12.1.0 cpe:2.3:a:oracle:flexcube_private_banking:12.1.0:*:*:*:*:*:*:*
oracle retail_xstore_point_of_service 16.0.6 cpe:2.3:a:oracle:retail_xstore_point_of_service:16.0.6:*:*:*:*:*:*:*
oracle retail_xstore_point_of_service 17.0.4 cpe:2.3:a:oracle:retail_xstore_point_of_service:17.0.4:*:*:*:*:*:*:*
oracle retail_xstore_point_of_service 18.0.3 cpe:2.3:a:oracle:retail_xstore_point_of_service:18.0.3:*:*:*:*:*:*:*
oracle retail_xstore_point_of_service 19.0.2 cpe:2.3:a:oracle:retail_xstore_point_of_service:19.0.2:*:*:*:*:*:*:*
oracle retail_xstore_point_of_service 20.0.1 cpe:2.3:a:oracle:retail_xstore_point_of_service:20.0.1:*:*:*:*:*:*:*

References for CVE-2021-43859

URL Tags
http://www.openwall.com/lists/oss-security/2022/02/09/1 Mailing List Third Party Advisory
https://github.com/x-stream/xstream/commit/e8e88621ba1c85ac3b8620337dd672e0c0c3a846 Patch Third Party Advisory
https://github.com/x-stream/xstream/security/advisories/GHSA-rmr5-cpv2-vgjf Exploit Third Party Advisory
https://lists.debian.org/debian-lts-announce/2022/02/msg00018.html Mailing 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.html Patch Third Party Advisory
https://www.oracle.com/security-alerts/cpujul2022.html Patch Third Party Advisory
https://x-stream.github.io/CVE-2021-43859.html Exploit Vendor Advisory
https://lists.debian.org/debian-lts-announce/2024/12/msg00023.html
cvelogic Threat Intelligence