How severe is CVE-2020-27221?

CVE-2020-27221 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2020-27221 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (72nd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2020-27221?

CVE-2020-27221 affects Eclipse Openj9. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2020-27221?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.

When was CVE-2020-27221 published?

CVE-2020-27221 was published on 2021-01-21 and last updated on 2026-06-17.

CVE-2020-27221

CVE-2020-27221 is a critical-severity vulnerability in Eclipse Openj9 with a CVSS 3.x base score of 9.8. 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-787.

Key facts

Severity: Critical (CVSS 3.x base score 9.8)
CVSS v2: 7.5
EPSS exploit prediction: 2% (72nd percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-787
Affected product: Eclipse Openj9
Published: 2021-01-21
Last modified: 2026-06-17

Description

In Eclipse OpenJ9 up to and including version 0.23, there is potential for a stack-based buffer overflow when the virtual machine or JNI natives are converting from UTF-8 characters to platform encoding.

Frequently asked questions

What is CVE-2020-27221?: In Eclipse OpenJ9 up to and including version 0.23, there is potential for a stack-based buffer overflow when the virtual machine or JNI natives are converting from UTF-8 characters to platform encoding.
How severe is CVE-2020-27221?: CVE-2020-27221 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2020-27221 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (72nd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2020-27221?: CVE-2020-27221 affects Eclipse Openj9. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2020-27221?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
When was CVE-2020-27221 published?: CVE-2020-27221 was published on 2021-01-21 and last updated on 2026-06-17.

References

https://bugs.eclipse.org/bugs/show_bug.cgi?id=569763

Affected products (1)

cpe:2.3:a:eclipse:openj9:*:*:*:*:*:*:*:*

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