CVE-2021-21350 | XStream is vulnerable to an Arbitrary Code Execution attack

Exp

XStream is a Java library to serialize objects to XML and back again. In XStream before version 1.4.16, there is a vulnerability which may allow a remote attacker to execute arbitrary code only by manipulating the processed input stream. No user is affected, who followed the recommendation to setup XStream's security framework with a whitelist limited to the minimal required types. If you rely on XStream's default blacklist of the Security Framework, you will have to use at least version 1.4.16.

Published: 2021-03-23 Last update: 2025-05-23 Assigner: [email protected] Source: [email protected]
NVD Status：Analyzed，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2021-21350 is rated High Exploit Risk (70.2/100): CVSS Medium severity, with high exploitation likelihood (EPSS 8.76%, 92th percentile). 1 public exploit reference(s) are indexed (Exploit-DB). EPSS rose +1.65% over the last day, indicating growing attacker interest. 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-2021-21350

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

Exploit prediction scoring system (EPSS) score for CVE-2021-21350

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 2026-03-24 7.11% 8.76% +1.65%
2 2026-03-10 8.24% 7.11% -1.13%
3 2025-12-28 — 8.24% —

Full EPSS history (45 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2021-21350

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
5.3 3.1 MEDIUM
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:H/A:N 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:H)
Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:R)
A real person has to do something—click, install, enable—otherwise it doesn’t land.
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:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:N)
Service keeps running; no real outage angle.
 1.6 3.6 [email protected]
9.8 3.1 CRITICAL
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/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:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 5.9 [email protected]
7.5 2.0 HIGH
AV:N/AC:L/Au:N/C:P/I:P/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:P)
Partial confidentiality impact.
Integrity impact (I:P)
Partial integrity impact.
Availability impact (A:P)
Partial availability impact.
 10.0 6.4 [email protected]

Weakness enumeration for CVE-2021-21350

GitHub Security Advisory for CVE-2021-21350

GHSA-43gc-mjxg-gvrq · Severity: medium · Ecosystem: maven — XStream is vulnerable to an Arbitrary Code Execution attack

OS Trackers for CVE-2021-21350

vendor priority summary link
debian not yet assigned CVE-2021-21350 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-2021-21350
redhat high — https://access.redhat.com/security/cve/CVE-2021-21350
suse high CVE-2021-21350 severity important: SUSE including 247 source package names (5.0.0-beta1.2.122:xstream-1.4.16-3.8.1, 5.1.0.6.40:xstream-1.4.16-3.8.1, …), 280 product×package rows across 32 product lines (Container suse/manager/5.0/x86_64/server, Container suse/multi-linux-manager/5.1/x86_64/server, … (32 product lines)): Known Affected 231, Fixed 49. https://www.suse.com/security/cve/CVE-2021-21350/
ubuntu medium CVE-2021-21350 medium priority: Ubuntu including 1 source packages (libxstream-java), 14 status rows across 14 suites (bionic, focal, groovy, hirsute, impish, jammy, kinetic, lunar, mantic, noble, oracular, trusty, upstream, xenial): released 14. https://ubuntu.com/security/CVE-2021-21350

Affected software / configurations for CVE-2021-21350

Vendor Product Version Raw CPE
netapp oncommand_insight — cpe:2.3:a:netapp:oncommand_insight:-:*:*:*:*:*:*:*
apache activemq < 5.15.14 cpe:2.3:a:apache:activemq:*:*:*:*:*:*:*:*
apache activemq 5.16.0 cpe:2.3:a:apache:activemq:5.16.0:*:*:*:*:*:*:*
apache activemq 5.16.1 cpe:2.3:a:apache:activemq:5.16.1:*:*:*:*:*:*:*
apache jmeter < 5.5 cpe:2.3:a:apache:jmeter:*:*:*:*:*:*:*:*
xstream xstream < 1.4.16 cpe:2.3:a:xstream:xstream:*:*:*:*:*:*:*:*
debian debian_linux 9.0 cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*
debian debian_linux 10.0 cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:*
debian debian_linux 11.0 cpe:2.3:o:debian:debian_linux:11.0:*:*:*:*:*:*:*
fedoraproject fedora 33 cpe:2.3:o:fedoraproject:fedora:33:*:*:*:*:*:*:*
fedoraproject fedora 34 cpe:2.3:o:fedoraproject:fedora:34:*:*:*:*:*:*:*
fedoraproject fedora 35 cpe:2.3:o:fedoraproject:fedora:35:*:*:*:*:*:*:*
oracle banking_enterprise_default_management 2.10.0 cpe:2.3:a:oracle:banking_enterprise_default_management:2.10.0:*:*:*:*:*:*:*
oracle banking_enterprise_default_management 2.12.0 cpe:2.3:a:oracle:banking_enterprise_default_management:2.12.0:*:*:*:*:*:*:*
oracle banking_platform 2.4.0 cpe:2.3:a:oracle:banking_platform:2.4.0:*:*:*:*:*:*:*
oracle banking_platform 2.7.1 cpe:2.3:a:oracle:banking_platform:2.7.1:*:*:*:*:*:*:*
oracle banking_platform 2.9.0 cpe:2.3:a:oracle:banking_platform:2.9.0:*:*:*:*:*:*:*
oracle banking_platform 2.12.0 cpe:2.3:a:oracle:banking_platform:2.12.0:*:*:*:*:*:*:*
oracle banking_virtual_account_management 14.2.0 cpe:2.3:a:oracle:banking_virtual_account_management:14.2.0:*:*:*:*:*:*:*
oracle banking_virtual_account_management 14.3.0 cpe:2.3:a:oracle:banking_virtual_account_management:14.3.0:*:*:*:*:*:*:*
oracle banking_virtual_account_management 14.5.0 cpe:2.3:a:oracle:banking_virtual_account_management:14.5.0:*:*:*:*:*:*:*
oracle business_activity_monitoring 11.1.1.9.0 cpe:2.3:a:oracle:business_activity_monitoring:11.1.1.9.0:*:*:*:*:*:*:*
oracle business_activity_monitoring 12.2.1.3.0 cpe:2.3:a:oracle:business_activity_monitoring:12.2.1.3.0:*:*:*:*:*:*:*
oracle business_activity_monitoring 12.2.1.4.0 cpe:2.3:a:oracle:business_activity_monitoring:12.2.1.4.0:*:*:*:*:*:*:*
oracle communications_billing_and_revenue_management_elastic_charging_engine 12.0.0.3.0 cpe:2.3:a:oracle:communications_billing_and_revenue_management_elastic_charging_engine:12.0.0.3.0:*:*:*:*:*:*:*
oracle communications_policy_management 12.5.0 cpe:2.3:a:oracle:communications_policy_management:12.5.0:*:*:*:*:*:*:*
oracle communications_unified_inventory_management 7.3.2 cpe:2.3:a:oracle:communications_unified_inventory_management:7.3.2:*:*:*:*:*:*:*
oracle communications_unified_inventory_management 7.3.4 cpe:2.3:a:oracle:communications_unified_inventory_management:7.3.4:*:*:*:*:*:*:*
oracle communications_unified_inventory_management 7.3.5 cpe:2.3:a:oracle:communications_unified_inventory_management:7.3.5:*:*:*:*:*:*:*
oracle communications_unified_inventory_management 7.4.0 cpe:2.3:a:oracle:communications_unified_inventory_management:7.4.0:*:*:*:*:*:*:*
oracle communications_unified_inventory_management 7.4.1 cpe:2.3:a:oracle:communications_unified_inventory_management:7.4.1:*:*:*:*:*:*:*
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 webcenter_portal 11.1.1.9.0 cpe:2.3:a:oracle:webcenter_portal:11.1.1.9.0:*:*:*:*:*:*:*
oracle webcenter_portal 12.2.1.3.0 cpe:2.3:a:oracle:webcenter_portal:12.2.1.3.0:*:*:*:*:*:*:*
oracle webcenter_portal 12.2.1.4.0 cpe:2.3:a:oracle:webcenter_portal:12.2.1.4.0:*:*:*:*:*:*:*
oracle weblogic_server 12.1.3.0.0 cpe:2.3:a:oracle:weblogic_server:12.1.3.0.0:*:*:*:*:*:*:*
oracle weblogic_server 12.2.1.3.0 cpe:2.3:a:oracle:weblogic_server:12.2.1.3.0:*:*:*:*:*:*:*
oracle weblogic_server 12.2.1.4.0 cpe:2.3:a:oracle:weblogic_server:12.2.1.4.0:*:*:*:*:*:*:*
oracle weblogic_server 14.1.1.0.0 cpe:2.3:a:oracle:weblogic_server:14.1.1.0.0:*:*:*:*:*:*:*

References for CVE-2021-21350

URL Tags
http://x-stream.github.io/changes.html#1.4.16 Release Notes Third Party Advisory
https://github.com/x-stream/xstream/security/advisories/GHSA-43gc-mjxg-gvrq Third Party Advisory
https://lists.apache.org/thread.html/r8244fd0831db894d5e89911ded9c72196d395a90ae655414d23ed0dd%40%3Cusers.activemq.apache.org%3E Issue Tracking Mailing List Third Party Advisory
https://lists.apache.org/thread.html/r9ac71b047767205aa22e3a08cb33f3e0586de6b2fac48b425c6e16b0%40%3Cdev.jmeter.apache.org%3E Issue Tracking Mailing List Third Party Advisory
https://lists.debian.org/debian-lts-announce/2021/04/msg00002.html Mailing List Third Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/22KVR6B5IZP3BGQ3HPWIO2FWWCKT3DHP/ Mailing List Third Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/PVPHZA7VW2RRSDCOIPP2W6O5ND254TU7/ Mailing List Third Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/QGXIU3YDPG6OGTDHMBLAFN7BPBERXREB/ Mailing List Third Party Advisory
https://security.netapp.com/advisory/ntap-20210430-0002/ Third Party Advisory
https://www.debian.org/security/2021/dsa-5004 Mailing List Third Party Advisory
https://www.oracle.com//security-alerts/cpujul2021.html Third Party Advisory
https://www.oracle.com/security-alerts/cpujan2022.html Patch Vendor Advisory
https://www.oracle.com/security-alerts/cpuoct2021.html Third Party Advisory
https://x-stream.github.io/CVE-2021-21350.html Exploit Third Party Advisory
https://x-stream.github.io/security.html#workaround Mitigation Third Party Advisory
cvelogic Threat Intelligence