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NVD / CVE Program· CNA GitHub_M

CVE-2021-21345: XStream is vulnerable to a Remote Command Execution attack

Noroxi assessment

Priority: This week (action score 61/100)

  • A ready-made attack module is public (Nuclei); exploiting it takes no special expertise.
  • Public proof-of-concept code exists (GitHub); there is no record of exploitation in the wild.
  • Probability of exploitation in the next 30 days: 72.3% (FIRST EPSS); higher than 99.4% of all records.
  • Anyone who can reach it over the internet can trigger it. A low-privileged account is enough. No user action is required. No special conditions are required; it is repeatable.
  • Fixed version: libxstream-java (Debian:12) 1.4.15-2; libxstream-java (Debian:9) 1.4.11.1-1+deb9u2; com.thoughtworks.xstream:xstream (Maven) 1.4.16.
  • Severity is disputed: the assigning authority (CNA) scores it 5.8, NVD 9.9.
  • Mentioned 3 times in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Don’t wait for the next maintenance window. Upgrade to libxstream-java (Debian:12) 1.4.15-2; libxstream-java (Debian:9) 1.4.11.1-1+deb9u2; com.thoughtworks.xstream:xstream (Maven) 1.4.16 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

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 who has sufficient rights to execute commands of the host 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.

CriticalCVSS 9.9 · v3.1—Proof of concept Fix available
Published
Mar 23, 2021
Updated
Oct 7, 2026
EPSS
72.3% · 99th percentile

Report tools

JSON

Action score

61

This week

Don’t wait for the next maintenance window.

CVSS
39 / 40 · 9.9 / 10
CISA KEV
0 / 30 · Not listed
EPSS
22 / 30 · 72.3%

CISA SSVC decision

Exploitation
none
Automatable
no
Technical impact
total

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
9.9
CNA · GitHub_M
5.8
4.1 point gap

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

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • Proof of concept exists, no weaponized module
  • A fix has been released

If any of these changes, we'll tell you in the daily email digest.

Follow CVE-2021-21345

When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
xstreamxstream
netapponcommand insight
apacheactivemq
apachejmeter
debiandebian linux
fedoraprojectfedora
oraclebanking enterprise default management
oraclebanking platform
oraclebanking virtual account management
oraclebusiness activity monitoring
oraclecommunications billing and revenue management elastic charging engine
oraclecommunications policy management

and 4 more

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • apache activemqbefore 5.15.14
  • apache activemq5.16.0
  • apache activemq5.16.1
  • apache jmeterbefore 5.5
  • debian debian linux10.0
  • debian debian linux11.0
  • debian debian linux9.0
  • fedoraproject fedora33
  • fedoraproject fedora34
  • fedoraproject fedora35
  • netapp oncommand insightall versions
  • oracle banking enterprise default management2.10.0
  • oracle banking enterprise default management2.12.0
  • oracle banking platform2.12.0
  • oracle banking platform2.4.0
  • oracle banking platform2.7.1
  • oracle banking platform2.9.0
  • oracle banking virtual account management14.2.0
  • oracle banking virtual account management14.3.0
  • oracle banking virtual account management14.5.0

Versions reported by the vendor

Affected version ranges reported by the assigning authority (GitHub_M). Independent of NVD's CPE analysis and usually ahead of it.

  • x-stream xstream

    • < 1.4.16affected

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Debian:12libxstream-javabefore 1.4.15-21.4.15-2
Debian:9libxstream-javabefore 1.4.11.1-1+deb9u21.4.11.1-1+deb9u2
Mavencom.thoughtworks.xstream:xstreambefore 1.4.161.4.16
openSUSE:Leap 15.2xstreambefore 1.4.16-lp152.2.6.11.4.16-lp152.2.6.1
openSUSE:Leap 15.3xstreambefore 1.4.16-3.8.11.4.16-3.8.1
openSUSE:Tumbleweedxstreambefore 1.4.18-1.11.4.18-1.1
Red Hat:enterprise_linux:7::clientxstreambefore 0:1.3.1-13.el7_90:1.3.1-13.el7_9
Red Hat:enterprise_linux:7::clientxstream-javadocbefore 0:1.3.1-13.el7_90:1.3.1-13.el7_9
SUSE:Linux Enterprise Module for Development Tools 15 SP2xstreambefore 1.4.16-3.8.11.4.16-3.8.1

Same product

xstream: all records

Other highest-scoring records for the same primary product.

  • CVE-2021-39144XStream is vulnerable to a Remote Command Execution attackKEV
    93Now
  • CVE-2019-10173It was found that xstream API version 1.4.10 before 1.4.11 introduced a regression for a previous deserialization flaw.
    68This week
  • CVE-2013-7285Xstream API versions up to 1.4.6 and version 1.4.10, if the security framework has not been initialized, may allow a remote attacker to run
    64This week

Published before and after this one in the same product

  • ← EarlierCVE-2021-21343Mar 23, 2021 · XStream is vulnerable to an Arbitrary File Deletion on the local host when unmarshalling as long as the executing process has sufficient rights
    44Plan
  • ← EarlierCVE-2021-21344Mar 23, 2021 · XStream is vulnerable to an Arbitrary Code Execution attack
    62This week
  • Later →CVE-2021-21346Mar 23, 2021 · XStream is vulnerable to an Arbitrary Code Execution attack
    62This week

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
debian:libxstream-java1.4.15-2 · Debian:12Package registry (OSV)
Maven:com.thoughtworks.xstream:xstream1.4.16Package registry (OSV)
opensuse:xstream1.4.16-lp152.2.6.1 · openSUSE:Leap 15.2Package registry (OSV)
red hat:xstream0:1.3.1-13.el7_9 · Red Hat:enterprise_linux:7::clientPackage registry (OSV)
red hat:xstream-javadoc0:1.3.1-13.el7_9 · Red Hat:enterprise_linux:7::clientPackage registry (OSV)
suse:xstream1.4.16-3.8.1 · SUSE:Linux Enterprise Module for Development Tools 15 SP2Package registry (OSV)

Exploit status

Proof of concept available

A public proof of concept or detection signature exists. Exploit knowledge is out there; don't delay patching.

Evidence

  • Nuclei detection template ×1
  • Proof-of-concept repository on GitHub ×1

Noroxi does not host or link to exploit code. Metasploit module names and Nuclei template ids are shown (names, not code); Exploit-DB entries and PoC repositories are given as counts only.

Public exploit evidence
SourceKindDate
Nuclei detection templateNuclei template CVE-2021-21345 —
Proof-of-concept repository on GitHubstars:02025-08-23

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

  1. Published
  2. First PoC+1614 d
  3. TodayNov 10, 2026+2058 d

No history yet (it accumulates with the daily EPSS job).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

National notice (Türkiye Cybersecurity Directorate / USOM)

Official security notices citing this record; remediation advice is on the agency's page.

All national notices →

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • A low-privileged account is enough.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
high · data can be read
Integrity
high · data or configuration can be modified
Availability
high · the service can be disrupted

Impact can extend beyond the vulnerable component (scope changes).

Attack vector
Network
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Changed
Confidentiality impact
High
Integrity impact
High
Availability impact
High

Weakness class (CWE)

CWE-94 · Improper Control of Generation of Code ('Code Injection')

CVSS vector

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

nvd-primary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

Change log

  1. SSVC exploitation— → none
  2. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Show all references (14 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records