🛡️ CVE-2021-39140 — xstream

⚪ Unknown ✅ No Known Exploit CWE-502 OSV
N/A
CVSS Score
0 Low4 Medium7 High9 Critical10

Description

XStream can cause a Denial of Service

Impact

The vulnerability may allow a remote attacker to allocate 100% CPU time on the target system depending on CPU type or parallel execution of such a payload resulting in a denial of service 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.

Patches

XStream 1.4.18 uses no longer a blacklist by default, since it cannot be secured for general purpose.

Workarounds

See [workarounds](https://x-stream.github.io/security.html#workaround) for the different versions covering all CVEs.

References

See full information about the nature of the vulnerability and the steps to reproduce it in XStream's documentation for [CVE-2021-39140](https://x-stream.github.io/CVE-2021-39140.html).

Credits

The vulnerability was discovered and reported by Lai Han of nsfocus security team.

For more information

If you have any questions or comments about this advisory:

  • Open an issue in [XStream](https://github.com/x-stream/xstream/issues)
  • Contact us at [XStream Google Group](https://groups.google.com/group/xstream-user)

How this vulnerability can be exploited

This issue can be reached over the network, attack complexity is low, an attacker needs low-level privileges on the target. No user interaction is required. The scope is unchanged, so the impact stays within the vulnerable component. Rated impact: confidentiality none, integrity none, availability high.

Weakness class

CVE-2021-39140 is classified as CWE-502: Deserialization of Untrusted Data. Serialised data from an untrusted source is reconstructed into objects, which can trigger code during the process.

Affected software

CVE-2021-39140 is recorded against 1 package.

  • com.thoughtworks.xstream:xstream (fixed in 1.4.18)

Timeline and source

Published on 25 August 2021 and last revised on 8 July 2026. No public exploit is currently recorded for this entry. Record sourced from OSV.

References

github.com (Web)
nvd.nist.gov (Advisory)
github.com (Package)
lists.debian.org (Web)
lists.fedoraproject.org (Web)
lists.fedoraproject.org (Web)
lists.fedoraproject.org (Web)
security.netapp.com (Web)
www.debian.org (Web)
www.oracle.com (Web)
www.oracle.com (Web)
www.oracle.com (Web)
x-stream.github.io (Web)

CVE-2021-39140 on other distributions

Each distribution ships its own build and its own fixed version. Pick the one you run:

Details

Severity Unknown
CVSS Score N/A
CVSS Vector CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
CWE CWE-502
Public Exploit ✅ No
Source OSV
Published 2021-08-25
Updated 2026-08-12
Modified 2026-07-08
Fix URL N/A

Affected Packages

Software From version Fixed in
com.thoughtworks.xstream:xstream — 1.4.18

References

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