CVE-2021-29505

XStream is vulnerable to a Remote Command Execution attack

CVSS 3.1 High 7.5

CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H

Description

XStream is software for serializing Java objects to XML and back again. A vulnerability in XStream versions prior to 1.4.17 may allow a remote attacker has sufficient rights to execute commands of the host only by manipulating the processed input stream. No user who followed the recommendation to setup XStream's security framework with a whitelist limited to the minimal required types is affected. The vulnerability is patched in version 1.4.17.

Key data

CVSS 3.1 High 7.5

Score published by GitHub_M in the CVE record.

CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H

Attack vector: Network
The vulnerable component can be reached over a network, possibly from the Internet.
Attack complexity: High
The attack depends on conditions outside the attacker's control, so it takes preparation.
Privileges required: Low
A basic user account is needed.
User interaction: None
No action from any user is needed.
Scope: Unchanged
The impact stays within the vulnerable component.
Confidentiality impact: High
Serious or total effect on the secrecy of data.
Integrity impact: High
Serious or total effect on the trustworthiness of data.
Availability impact: High
Serious or total effect on availability.

Metric	Value	What it means
Attack vector	Network	The vulnerable component can be reached over a network, possibly from the Internet.
Attack complexity	High	The attack depends on conditions outside the attacker's control, so it takes preparation.
Privileges required	Low	A basic user account is needed.
User interaction	None	No action from any user is needed.
Scope	Unchanged	The impact stays within the vulnerable component.
Confidentiality impact	High	Serious or total effect on the secrecy of data.
Integrity impact	High	Serious or total effect on the trustworthiness of data.
Availability impact	High	Serious or total effect on availability.

CVSS is owned and managed by FIRST.Org, Inc. (FIRST) and is used by permission. Each CVSS score on this site is shown together with its vector string, as published in the CVE record by the source named next to it. Learn more at first.org/cvss.

EPSS

Exploit Prediction Scoring System by FIRST: an estimate of the probability that exploitation activity will be observed in the next 30 days.

Score: 0.77232 (77.2% probability)
Percentile: 99.6%
Scores of: Nov 10, 2026
Model: v2026.06.15

CISA assessment as of Oct 7, 2026

Stakeholder-Specific Vulnerability Categorization (SSVC) decision points added by CISA.

Automatable: no
Technical impact: total

Weakness (CWE)

CWE catalog version 5.0.

CWE-94Improper Control of Generation of Code
CWE-502Deserialization of Untrusted Data

Affected products

Products listed in the CVE record, as the CNA published them.

x-stream xstream
- affected: < 1.4.17

References

Links listed in the CVE record. They lead to other sites, which CubePath does not control.

Timeline

ID reservedMar 30, 2021
Record publishedMay 28, 2021
Record last updatedOct 7, 2026

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Data from the CVE Program (MITRE), CISA KEV and FIRST EPSS. CVSS is owned by FIRST and used by permission. Not affiliated with or endorsed by MITRE, CISA or FIRST. Data as of Nov 10, 2026, 19:52 UTC. Sources and licenses