Debian LinuxOperating system · Debian
CVE-2021-39144
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedXStream 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 it cannot be secured for general purpose.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · high confidenceThis is a deserialization vulnerability in XStream (versions prior to 1.4.18) that allows remote code execution through manipulated XML input streams. Attackers can execute arbitrary commands on the host if they have sufficient rights to control the processed input stream. The vulnerability is exploitable only when users have not configured XStream's security framework with a whitelist of allowed types.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE data
Debian LinuxOperating system
= 9.0= 10.0= 11.0
FedoraOperating system
= 33= 34= 35< 1.4.18all versions= 12.2.1.4.0= 11.3.2= 11.3= 12.0= 1.9.0CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Network
- Complexity
- High
- Privileges
- Low
- User interaction
- None
- Scope
- Changed
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Locate XStream library in the environmentSearch for xstream jar files (e.g., xstream-*.jar) in application directories, lib folders, or dependency manifests (pom.xml, build.gradle, requirements.txt for JVM languages). Use commands like 'find . -name "xstream*.jar"' or grep dependency files for xstream.Affected if XStream library is present in the environment
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Determine installed XStream versionInspect the jar filename for version number, check META-INF/MANIFEST.MF inside the jar for Implementation-Version, or review the dependency management file (pom.xml, build.gradle) for the xstream version declaration.Affected if The version is lower than 1.4.18 (e.g., 1.4.17, 1.4.16, etc.)
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Identify if application deserializes XML input streamsReview application source code for XStream usage patterns: look for XStream object instantiation (new XStream()) followed by fromXML() calls, or XML unmarshalling operations. Check for endpoints or functions that accept XML payloads processed by XStream.Affected if The application uses XStream.fromXML() or similar methods to process incoming XML data
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Confirm default blacklist security is in useInspect code for XStream security configuration. Look for absence of setupDefaultSecurity() with a whitelist, or check if only addTypePermission() calls use blacklist patterns (e.g., anyBlacklist, anySerializationType). Default vulnerable config has no explicit whitelist.Affected if XStream uses default blacklist configuration without an explicit whitelist of allowed types
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Check running service exposureIdentify if the XStream processing endpoint is accessible to network callers or accepts input from untrusted sources. Review web service endpoints, APIs, or file processing services that use XStream.Affected if The XStream processing functionality is exposed to untrusted input sources
You are affected if XStream library version lower than 1.4.18 is present AND your application uses XStream to process XML input from untrusted sources with the default blacklist security model.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
dbcve · scoped1.4.18
Upgrade to XStream 1.4.18 or later and configure a whitelist-based security framework that limits allowed types to the minimal set required by the application, as blacklist-based approaches cannot be secured for general-purpose use.
XStream 1.4.18 or later
- Identify all applications and dependencies using XStream library in your environment
- Locate the XStream JAR files or Maven/Gradle dependencies in your projects
- For Maven projects: Update the XStream dependency version to 1.4.18 or later in pom.xml (e.g., <groupId>com.thoughtworks.xstream</groupId><artifactId>xstream</artifactId><version>1.4.18</version>)
- For Gradle projects: Update to implementation 'com.thoughtworks.xstream:xstream:1.4.18' or later
- For standalone JAR deployments: Replace existing xstream JAR with version 1.4.18 or newer
- Rebuild and recompile all affected applications
- Test all XML deserialization functionality to ensure compatibility with the upgrade
- Deploy the updated applications to production environments
Generated from the published advisory — verify against the referenced sources before acting.
Fix this in Debian Linux
Exploited in the wild — priority engagement
- Consultation8.0 h
- Implementation16.0 h
- Testing12.0 h
- Review / QA4.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $11,200.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-39144 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2021-39144 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
- No weaponised exploit code, or anything meant to cause harm
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