How severe is CVE-2021-20089?

CVE-2021-20089 has a CVSS 3.x base score of 8.8, rated high severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2021-20089 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (73rd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-20089?

CVE-2021-20089 affects Purl Project Purl. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-20089?

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

When was CVE-2021-20089 published?

CVE-2021-20089 was published on 2021-04-23 and last updated on 2026-06-17.

CVE-2021-20089

CVE-2021-20089 is a high-severity vulnerability in Purl Project Purl with a CVSS 3.x base score of 8.8. 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-1321.

Key facts

Severity: High (CVSS 3.x base score 8.8)
CVSS v2: 6.5
EPSS exploit prediction: 2% (73rd percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-1321
Affected product: Purl Project Purl
Published: 2021-04-23
Last modified: 2026-06-17

Description

Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution') in purl 2.3.2 allows a malicious user to inject properties into Object.prototype.

Frequently asked questions

What is CVE-2021-20089?: Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution') in purl 2.3.2 allows a malicious user to inject properties into Object.prototype.
How severe is CVE-2021-20089?: CVE-2021-20089 has a CVSS 3.x base score of 8.8, rated high severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2021-20089 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (73rd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-20089?: CVE-2021-20089 affects Purl Project Purl. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-20089?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2021-20089 published?: CVE-2021-20089 was published on 2021-04-23 and last updated on 2026-06-17.

References

https://github.com/BlackFan/client-side-prototype-pollution/blob/master/pp/purl.md

Affected products (1)

cpe:2.3:a:purl_project:purl:2.3.2:*:*:*:*:*:*:*

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