Security readout for executives and security teams
Plain-English summary
XStream before 1.4.18 can be abused when an application processes attacker-controlled XML. A successful attack can lead to arbitrary code execution, meaning full compromise of confidentiality, integrity, and availability for the affected application. Organizations using XStream safely with a strict type whitelist are specifically noted as not affected by this issue.
Executive priority
Treat this as a high-priority dependency risk where XStream handles external XML. It can become application-level code execution, but evidence provided does not support emergency active-exploitation handling. Patch or isolate exposed parsing paths and require owners to prove whitelist-based hardening.
Technical view
The flaw affects x-stream XStream versions before 1.4.18 and is associated with unsafe deserialization and remote code loading behavior. The CVSS 3.1 score is 8.5 with network attack vector, high complexity, low privileges, no user interaction, scope change, and high C/I/A impact.
Likely exposure
Exposure is most likely in Java applications or vendor products that include XStream and deserialize XML streams influenced by users, integrations, queues, or external services. Debian, Fedora, Oracle, and NetApp advisories indicate downstream packaging and product relevance, but the bundle does not enumerate every affected product.
Exploitation context
The provided sources do not show CISA KEV listing or active exploitation evidence. The advisory says a remote attacker may manipulate the processed input stream to load and execute arbitrary code from a remote host, but attack complexity is rated high and low privileges are required.
Researcher notes
Focus validation on deserialization boundaries, XStream security configuration, and bundled dependency discovery. The key control is a narrow type whitelist; XStream 1.4.18 changed the default away from blacklist-based security because general-purpose blacklist protection was not considered securable.
Mitigation direction
- Upgrade XStream to 1.4.18 or a vendor-supported fixed package.
- Configure XStream's security framework with a minimal required type whitelist.
- Check Debian, Fedora, Oracle, and NetApp guidance for packaged or bundled exposure.
- Prioritize systems parsing externally influenced XML before internal-only batch jobs.
- Remove unused XML deserialization paths where XStream is no longer required.
Validation and detection
- Inventory direct and transitive dependencies for XStream versions before 1.4.18.
- Review application code for XStream processing of untrusted or semi-trusted XML.
- Confirm a restrictive allowlist is configured for required application types only.
- Verify distribution packages match Debian or Fedora fixed advisory versions.
- Check affected vendor products against Oracle and NetApp advisories.
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-2021-39151 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-hph2-m3g5-xxv4CVE reference · x_refsource_CONFIRM
- https://x-stream.github.io/CVE-2021-39151.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.