Vulnerability · CVE-2021-39152
XStream XStream Deserialization of Untrusted Data
Published Feb 14, 2026 · corrected/updated Feb 14, 2026 · XStream XStream · evidence confidence very high
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 rely on XStream's default blacklist of the [Security Framework](https://x-stream.github.io/security.html#framework), you will have to use at least ve
Grounded briefings
Catalog interpretations for three audiences. Each brief cites ingested metadata and the original advisories below. They are not independent research and they do not invent exploit steps.
Executive
CVE-2021-39152 is a unknown public vulnerability record for XStream XStream. CISA lists it as known exploited. Published remediation guidance: Apply remediations or mitigations per vendor instructions or discontinue use of the product if remediation or mitigations are unavailable. This summary is a catalog interpretation of the ingested metadata and cites the original advisories below.
System administrator
Identify whether XStream XStream is in your estate, then compare installed versions with the affected ranges. Affected packages or ranges on record: XStream XStream. Published remediation guidance: Apply remediations or mitigations per vendor instructions or discontinue use of the product if remediation or mitigations are unavailable. Prefer the vendor or distribution advisory linked in Sources before changing production systems. This is a catalog interpretation, not a runbook.
Security analyst
Signals on file: no CVSS/EPSS yet. CISA lists it as known exploited. Sources contributing to this record: cve_org, vulncheck_kev. Public exploit references, when present, are outbound links only and are not proof of active exploitation. This is a catalog interpretation of stored metadata.
Exploitation and remediation
Exploitation evidence
Confirmed in CISA KEV since Feb 14, 2026. Listed in CISA KEV and VulnCheck KEV.
Patch and remediation
Apply remediations or mitigations per vendor instructions or discontinue use of the product if remediation or mitigations are unavailable.
Safe detection guidance
Compare installed versions with the affected ranges below and verify the advisory from the original publisher. This site stores metadata and outbound links only; it does not ship exploit code or proof-of-concept payloads.
Code
The project this record applies to. Exploit listings stay in References.
No public source repository is identified for this product.
Timeline
Detection, updates, and resolution for this record.
Feb 14, 2026 · VulnCheck KEV
Detected
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 white
Feb 14, 2026 · CISA KEV
Known exploited
Apply remediations or mitigations per vendor instructions or discontinue use of the product if remediation or mitigations are unavailable.
Affected
- vendor XStream XStreamversion unspecified
Sources
- CVE.orgVulnerability recordCVE-2021-39152
Official CVE identifier
cve.org - VulnCheck KEVConfirmed exploitationCVE-2021-39152
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
vulncheck.com