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CVE-2021-39150: XStream is a simple library to serialize objects to XML and back again

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This week
HIGH 8.5WATCHLISTUPGRADEMITIGATEMITIGATE

CVE-2021-39150 is a high-severity flaw (CVSS 8.5) affecting xstream, fedora, debian linux. 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 to request data from internal resources that are not publicly available only by manipulating the processed input stream with a Java runtime version 14 to 8. 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

Why this priority

  • High severity
  • 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 chance3.4% (top 11%)
CISA exploited listNo
WeaknessCWE-502, CWE-918
Published2021-08-23
Last modified2026-10-07
Publisher (CNA): GitHub, Inc. · Vendor: debian · fedoraproject · netapp · oracle · xstream

Share: LinkedIn · X · Reddit

Last updated 2026-10-07 · 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.
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.
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.
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.
Verify at the official source NVD · CVE Program · 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-2021-39150?

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

Is CVE-2021-39150 being exploited?

CVE-2021-39150 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2021-39150 affect?

CVE-2021-39150 affects xstream, fedora, debian linux. 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 to request data from internal resources that are not publicly available only by manipulating the pro

How urgent is CVE-2021-39150?

Priority 62/100. High severity; Public exploit reference; On your watchlist

Software pages

Java vulnerabilities · Debian vulnerabilities

Related CVEs

References

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