Security readout for executives and security teams
Plain-English summary
XStream versions before 1.4.18 can let an attacker who can influence processed XML trigger arbitrary code execution. Business risk is highest where applications deserialize untrusted or partner-supplied XML without XStream’s recommended type whitelist.
Executive priority
Treat as high priority for Java services that process external XML. Patch or validate configuration promptly, but urgency should be driven by whether XStream is reachable with attacker-controlled input and whether a strict whitelist is enforced.
Technical view
The flaw is unsafe deserialization in XStream, mapped to CWE-502 and CWE-434. Affected versions are x-stream/xstream before 1.4.18. The CVSS 3.1 score is 8.5 with high complexity, low privileges, no user interaction, and high confidentiality, integrity, and availability impact.
Likely exposure
Exposure is likely in Java applications or vendor products bundling XStream before 1.4.18, especially where XML input is accepted from users, integrations, queues, imports, or APIs. Systems using a strict minimal whitelist are described as not affected.
Exploitation context
The supplied sources do not show CISA KEV listing or active exploitation. The vendor describes remote code execution by manipulating the processed input stream. Practical exposure depends on reachable XML deserialization paths and security framework configuration.
Researcher notes
Do not assume every XStream installation is exploitable. The key research questions are version, reachable deserialization path, trust boundary of the XML stream, and whether the security framework restricts allowed types to the minimum needed.
Mitigation direction
- Upgrade XStream to 1.4.18 or later where directly managed.
- Configure XStream’s security framework with a minimal required type whitelist.
- Apply distribution or vendor updates for packaged XStream dependencies.
- Check Oracle, NetApp, Debian, and Fedora advisories for affected bundled products.
- Prioritize internet-facing or partner-facing XML processing services.
Validation and detection
- Inventory direct and transitive XStream versions across applications and packages.
- Confirm no deployed dependency resolves to XStream before 1.4.18.
- Review XML deserialization entry points for untrusted or partner-controlled input.
- Verify XStream allowlists are minimal and required for application behavior.
- Confirm vendor advisory updates are applied for third-party products.
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-434: File access and web shell behavior lookup
File traversal and upload weaknesses can lead teams to review file, web shell, execution, and collection 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-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 lookupExecution behavior lookup
The CVE wording references code or command execution, so execution technique review may help defensive triage. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupCVE-2021-39146 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
- No
- 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.
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-p8pq-r894-fm8fCVE reference · x_refsource_CONFIRM
- https://x-stream.github.io/CVE-2021-39146.htmlCVE reference · x_refsource_MISC
- [debian-lts-announce] 20210929 [SECURITY] [DLA 2769-1] libxstream-java security updateCVE reference · mailing-list, x_refsource_MLIST
- FEDORA-2021-fbad11014aCVE reference · vendor-advisory, x_refsource_FEDORA
- FEDORA-2021-d894ca87dcCVE reference · vendor-advisory, x_refsource_FEDORA
- FEDORA-2021-5e376c0ed9CVE reference · vendor-advisory, x_refsource_FEDORA
- DSA-5004CVE reference · vendor-advisory, x_refsource_DEBIAN
- https://www.oracle.com/security-alerts/cpujan2022.htmlCVE reference · x_refsource_MISC
- https://security.netapp.com/advisory/ntap-20210923-0003/CVE reference · x_refsource_CONFIRM
- https://www.oracle.com/security-alerts/cpuapr2022.htmlCVE reference · x_refsource_MISC
- https://www.oracle.com/security-alerts/cpujul2022.htmlCVE reference · x_refsource_MISC
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.
Unrestricted Upload of File with Dangerous Type
Unrestricted Upload of File with Dangerous Type represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.
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.