Security readout for executives and security teams
Plain-English summary
XStream before 1.4.18 can let an attacker with some access make a vulnerable application run commands on the host by sending manipulated XML input. The business risk is highest where XStream processes untrusted data or is embedded in vendor products.
Executive priority
Prioritize remediation for internet-facing or partner-facing systems and vendor appliances using XStream. KEV status means this should be handled as an urgent vulnerability management item, not routine backlog work.
Technical view
This is a deserialization/code execution issue in x-stream XStream versions before 1.4.18. The CVSS vector is network reachable, high complexity, low privileges, no user interaction, scope changed, with high confidentiality, integrity, and availability impact.
Likely exposure
Java applications or packaged products using XStream below 1.4.18 are the primary exposure. Systems are less exposed if XStream's security framework was already configured with a whitelist limited to required types.
Exploitation context
The source bundle marks this CVE as in CISA KEV, so treat exploitation as confirmed. Public references also include a Packet Storm entry for VMware NSX Manager, but affected downstream product scope must be verified from vendor advisories.
Researcher notes
The strongest evidence is the upstream advisory and XStream CVE page. The bundle confirms affected versions before 1.4.18 and whitelist-based protection. Downstream vendor exposure is referenced but requires product-specific confirmation.
Mitigation direction
- Upgrade XStream to 1.4.18 or later where directly managed.
- Apply vendor or distribution updates for libxstream-java and embedded XStream products.
- Configure XStream's security framework with a minimal required-type whitelist.
- Identify and prioritize endpoints processing untrusted XML through XStream.
- Check Oracle, NetApp, Debian, and Fedora advisories for product-specific guidance.
Validation and detection
- Inventory application dependencies for xstream or libxstream-java versions below 1.4.18.
- Review code paths where XStream deserializes XML from users, partners, or network services.
- Confirm XStream type permissions are whitelist-based and limited to required classes.
- Check vendor product advisories for embedded XStream exposure and fixed versions.
- Verify patched deployments through dependency reports or package manager evidence.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-502: Code execution behavior lookup
Code execution and unsafe deserialization weaknesses often justify reviewing execution behavior and process telemetry. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCWE-94: Code execution behavior lookup
Code execution and unsafe deserialization weaknesses often justify reviewing execution behavior and process telemetry. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCVE-2021-39144 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- High
- CVSS
- 8.5 (3.1)
- Known Exploited
- Yes
- Published
Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CISA KEV status
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H1.86Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
8.5HighVector: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H
Source materials
- CVE List V5 sourceCVE List V5
- https://github.com/x-stream/xstream/security/advisories/GHSA-j9h8-phrw-h4fhCVE reference
- https://x-stream.github.io/CVE-2021-39144.htmlCVE reference
- [debian-lts-announce] 20210929 [SECURITY] [DLA 2769-1] libxstream-java security updateCVE reference · mailing-list
- FEDORA-2021-fbad11014aCVE reference · vendor-advisory
- FEDORA-2021-d894ca87dcCVE reference · vendor-advisory
- FEDORA-2021-5e376c0ed9CVE reference · vendor-advisory
- DSA-5004CVE reference · vendor-advisory
- https://www.oracle.com/security-alerts/cpujan2022.htmlCVE reference
- https://security.netapp.com/advisory/ntap-20210923-0003/CVE reference
- https://www.oracle.com/security-alerts/cpuapr2022.htmlCVE reference
- https://www.oracle.com/security-alerts/cpujul2022.htmlCVE reference
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-39144CVE reference · government-resource
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Deserialization of Untrusted Data
Deserialization of Untrusted Data represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.
Improper Control of Generation of Code ('Code Injection')
Improper Control of Generation of Code ('Code Injection') represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.