🛡️ CVE-2021-39151 — xstream

🟠 CVSS 8.0 — High ✅ No Known Exploit CWE-434 OSV
8.0
CVSS Score
0 Low4 Medium7 High9 Critical10

Description

XStream is vulnerable to an Arbitrary Code Execution attack

Impact

The vulnerability may allow a remote attacker to load and execute arbitrary code from a remote 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.

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-2021-39151](https://x-stream.github.io/CVE-2021-39151.html).

Credits

Smi1e of DBAPPSecurity WEBIN Lab found and reported the issue to XStream and provided the required information to reproduce it.

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 high, an attacker needs low-level privileges on the target. No user interaction is required. The scope is changed, meaning a successful attack can affect components beyond the vulnerable one. Rated impact: confidentiality high, integrity high, availability high.

Weakness class

CVE-2021-39151 is classified as CWE-434: Unrestricted Upload of File with Dangerous Type. Uploads are accepted without restricting type, so an executable file can be placed where the server will run it.

Affected software

CVE-2021-39151 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-2021-39151 on other distributions

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

Details

Severity HIGH
CVSS Score 8.0
CVSS Vector CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H
CWE CWE-434
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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