Answer in brief
CVE-2021-39144 records a High severity vulnerability in XStream is vulnerable to a Remote Command Execution attack. The current sources mark it as known exploited. The current feed maps x-stream/xstream (generic). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
Answer in brief
CVE-2021-39144 records a High severity vulnerability in XStream is vulnerable to a Remote Command Execution attack. The current sources mark it as known exploited. The current feed maps x-stream/xstream (generic). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
A CVSS score is not reported in the current record. Known-exploitation status makes exposure review time-sensitive. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps x-stream/xstream (generic). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| x-stream/xstreamgeneric | < 1.4.18 | Not reported |
Published upstream
Aug 23, 2021
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Oct 21, 2025
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
May 24, 2026
Added to CISA KEV
Mar 10, 2023
Evidence: source:kev:kev:kev:recordXStream 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.
Quoted source text, attributed separately from HOL analysis.
A CVSS score is not reported in the current record. Known-exploitation status makes exposure review time-sensitive. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps x-stream/xstream (generic). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| x-stream/xstreamgeneric | < 1.4.18 | Not reported |
Published upstream
Aug 23, 2021
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Oct 21, 2025
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
May 24, 2026
Added to CISA KEV
Mar 10, 2023
Evidence: source:kev:kev:kev:recordXStream 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.
Quoted source text, attributed separately from HOL analysis.