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CVE-2021-39144: XStream Remote Code Execution Vulnerability

90
Patch now
HIGH 8.5EXPLOITEDWATCHLISTUPGRADEMITIGATEMITIGATE

CVE-2021-39144 is a high-severity flaw (CVSS 8.5) affecting xstream, debian linux, fedora, reported as exploited in the wild. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

XStream is a simple library to serialize objects to XML and back again. In affected versions this vulnerability may allow a remote attacker 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. XStream 1.4.18 uses no longer a blacklist by default, since

Why this priority

  • High severity
  • EPSS top 1%: very likely to be exploited
  • Exploited in the wild (CISA KEV)
  • Public exploit reference
  • On your watchlist

A fixed release or distro patch exists.

Risk facts

CVSS score8.5 (High)
Attack vectorNetwork (remote)
Attack complexityHigh
Privileges neededLow
User interactionNone
EPSS exploit chance98.1% (top 1%)
CISA exploited listYes, fix due 2023-03-31
WeaknessCWE-94, CWE-502, CWE-306
Published2021-08-23
Last modified2026-06-17
Publisher (CNA): GitHub, Inc. · Vendor: debian · fedoraproject · netapp · oracle · xstream

Share: LinkedIn · X · Reddit

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

xstream xstream UPGRADE
Affected: < 1.4.18
Fixed in: 1.4.18
Safe to downgrade to: no unaffected older release
1. Check installed version
apt-cache policy xstream || rpm -q xstream || xstream --version
2. UPGRADE to 1.4.18 (Debian / Ubuntu)
sudo apt update && sudo apt install --only-upgrade xstream
2. UPGRADE (RHEL / Amazon Linux / Fedora)
sudo dnf upgrade xstream
Note
Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.
debian debian linux MITIGATE
Affected: 9.0 · 10.0 · 11.0
Fixed in: no fixed release known
Safe to downgrade to: a release before 9.0
Check your OS release
cat /etc/os-release; uname -r
Debian / Ubuntu
sudo apt update && sudo apt full-upgrade
RHEL / Amazon Linux / Fedora
sudo dnf upgrade --refresh
Windows
Install the latest cumulative update from Windows Update
If no patch exists yet
OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.
fedoraproject fedora MITIGATE
Affected: 33 · 34 · 35
Fixed in: no fixed release known
Safe to downgrade to: a release before 33
Check your OS release
cat /etc/os-release; uname -r
Debian / Ubuntu
sudo apt update && sudo apt full-upgrade
RHEL / Amazon Linux / Fedora
sudo dnf upgrade --refresh
Windows
Install the latest cumulative update from Windows Update
If no patch exists yet
OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.
netapp snapmanager MITIGATE
Affected: all versions
Fixed in: no fixed release known
Safe to downgrade to: no unaffected older release
1. Check installed version
apt-cache policy snapmanager || rpm -q snapmanager || snapmanager --version
No fixed or unaffected release known
Apply the vendor mitigation from the advisory, disable the affected feature, or restrict network access.
netapp snapmanager MITIGATE
Affected: all versions
Fixed in: no fixed release known
Safe to downgrade to: no unaffected older release
1. Check installed version
apt-cache policy snapmanager || rpm -q snapmanager || snapmanager --version
No fixed or unaffected release known
Apply the vendor mitigation from the advisory, disable the affected feature, or restrict network access.
oracle business activity monitoring DOWNGRADE
Affected: 12.2.1.4.0
Fixed in: no fixed release known
Safe to downgrade to: a release before 12.2.1.4.0
1. Check installed version
apt-cache policy business-activity-monitoring || rpm -q business-activity-monitoring || business-activity-monitoring --version
2. No fixed release: DOWNGRADE to a release before 12.2.1.4.0 (Debian / Ubuntu)
apt-cache madison business-activity-monitoring sudo apt install business-activity-monitoring=<VERSION_BEFORE_12.2.1.4.0> sudo apt-mark hold business-activity-monitoring
2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)
dnf --showduplicates list business-activity-monitoring sudo dnf downgrade business-activity-monitoring-<VERSION_BEFORE_12.2.1.4.0> sudo dnf versionlock add business-activity-monitoring
Downgrade risk
Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.
After downgrade
Restart the service, and keep the package held until a fixed release ships.

Exact fixes by distribution

A distro patch exists: prefer upgrading over downgrading.
Maven · com.thoughtworks.xstream:xstream · FIXED · 1.4.18 · vulnerable: < 1.4.18 · source
Set com.thoughtworks.xstream:xstream to 1.4.18 or later in pom.xml or build.gradle, then rebuild and redeploy.
Fedora 46 · bitcoin-core-selinux · FIXED · 0.3-2.fc46 · FEDORA-2026-51fc806272 · source
sudo dnf upgrade --advisory=FEDORA-2026-51fc806272
Fedora ELN · guestfs-tools · FIXED · 1.57.5-1.eln159 · FEDORA-2026-9577c5ec16 · source
sudo dnf upgrade --advisory=FEDORA-2026-9577c5ec16
Ubuntu 22.04 · libxstream-java · NOT AFFECTED
Ubuntu 20.04 · libxstream-java · FIXED · 1.4.11.1-1ubuntu0.3
sudo apt update && sudo apt install --only-upgrade libxstream-java dpkg --compare-versions "$(dpkg-query -W -f='${Version}' libxstream-java)" ge "1.4.11.1-1ubuntu0.3" && echo PATCHED || echo STILL-VULNERABLE
Debian 12 · libxstream-java · FIXED · 1.4.18-1
sudo apt update && sudo apt install --only-upgrade libxstream-java dpkg --compare-versions "$(dpkg-query -W -f='${Version}' libxstream-java)" ge "1.4.18-1" && echo PATCHED || echo STILL-VULNERABLE
Debian 13 · libxstream-java · FIXED · 1.4.18-1
sudo apt update && sudo apt install --only-upgrade libxstream-java dpkg --compare-versions "$(dpkg-query -W -f='${Version}' libxstream-java)" ge "1.4.18-1" && echo PATCHED || echo STILL-VULNERABLE
RHEL 7 · xstream · FIXED · xstream-1.3.1-16.el7_9
sudo dnf upgrade --advisory=RHSA-2021:3956 rpm -q xstream
Amazon Linux 2 · see advisory · FIXED · ALAS2-2021-1729 · source
sudo yum update --advisory=ALAS2-2021-1729

Public exploits and detection

Public code exists for this CVE. Treat unpatched systems as at risk, and only run PoCs in a lab.

Verify at the official source NVD · CVE Program · CISA KEV catalog · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2021-39144?

xstream: upgrade to 1.4.18; debian linux: mitigate or apply the listed mitigation; fedora: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2021-39144 being exploited?

Yes. CVE-2021-39144 is on the CISA Known Exploited Vulnerabilities list, so treat it as patch-now.

What does CVE-2021-39144 affect?

CVE-2021-39144 affects xstream, debian linux, fedora. Severity is high (CVSS 8.5). XStream is a simple library to serialize objects to XML and back again. In affected versions this vulnerability may allow a remote attacker has sufficient rights to execute commands of the host only by manipulating the processed input strea

How urgent is CVE-2021-39144?

Priority 90/100. High severity; EPSS top 1%: very likely to be exploited; Exploited in the wild (CISA KEV); Public exploit reference; On your watchlist

Software pages

Debian vulnerabilities

Related CVEs

References

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