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Vulnerability record · CVE-2021-39140 · published 23 August 2021

CVE-2021-39140: Xstream deserialization of untrusted data vulnerability

Xstream · Xstream

XStream is a simple library to serialize objects to XML and back again. In affected versions this 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. XStream 1.4.18 uses no longer a blacklist by default, since it cannot be secured for general purpose.

6.3 CVSS 3.1 Medium EPSS 5.9% · top 7.0% CWE-502 · Deserialization of untrusted dataCWE-835 · CWE-835
6.3CVSS 3.1 base score, v2 6.3
5.9%EPSS exploitation probability, 30 days
NoNot in CISA KEV
15Affected product versions listed by NVD
22References, 2 tagged exploit
17 Jun 2026Last modified by NVD

Description

XStream is a simple library to serialize objects to XML and back again. In affected versions this 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. XStream 1.4.18 uses no longer a blacklist by default, since it cannot be secured for general purpose.

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

Affected products

15 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://github.com/x-stream/xstream/security/advisories/GHSA-6wf9-jmg9-vxcc Third Party Advisory
https://lists.debian.org/debian-lts-announce/2021/09/msg00017.html Mailing ListThird Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/22KVR6B5IZP3BGQ3HPWIO2F Mailing List
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/PVPHZA7VW2RRSDCOIPP2W6O Mailing List
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/QGXIU3YDPG6OGTDHMBLAFN7 Mailing List
https://security.netapp.com/advisory/ntap-20210923-0003/ Third Party Advisory
https://www.debian.org/security/2021/dsa-5004 Third Party Advisory
https://www.oracle.com/security-alerts/cpuapr2022.html PatchThird Party Advisory
https://www.oracle.com/security-alerts/cpujan2022.html PatchThird Party Advisory
https://www.oracle.com/security-alerts/cpujul2022.html PatchThird Party Advisory
https://x-stream.github.io/CVE-2021-39140.html ExploitThird Party Advisory
https://github.com/x-stream/xstream/security/advisories/GHSA-6wf9-jmg9-vxcc Third Party Advisory
https://lists.debian.org/debian-lts-announce/2021/09/msg00017.html Mailing ListThird Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/22KVR6B5IZP3BGQ3HPWIO2F Mailing List
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/PVPHZA7VW2RRSDCOIPP2W6O Mailing List
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/QGXIU3YDPG6OGTDHMBLAFN7 Mailing List
https://security.netapp.com/advisory/ntap-20210923-0003/ Third Party Advisory
https://www.debian.org/security/2021/dsa-5004 Third Party Advisory
https://www.oracle.com/security-alerts/cpuapr2022.html PatchThird Party Advisory
https://www.oracle.com/security-alerts/cpujan2022.html PatchThird Party Advisory
https://www.oracle.com/security-alerts/cpujul2022.html PatchThird Party Advisory
https://x-stream.github.io/CVE-2021-39140.html ExploitThird Party Advisory

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Source: NIST National Vulnerability Database (record CVE-2021-39140), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.