CVE-2021-39140

CVE-2021-39140 is a medium-severity vulnerability in Xstream with a CVSS 3.x base score of 6.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-502.

Key facts

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.

Frequently asked questions

What is CVE-2021-39140?
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.
How severe is CVE-2021-39140?
CVE-2021-39140 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2021-39140 being actively exploited?
It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 6% (92nd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-39140?
CVE-2021-39140 primarily affects Xstream. In total, 36 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-39140?
Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2021-39140 published?
CVE-2021-39140 was published on 2021-08-23 and last updated on 2026-06-17.

References

Affected products (36)

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