How severe is CVE-2021-23663?

CVE-2021-23663 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity low, and availability low.

Is CVE-2021-23663 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (64th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-23663?

CVE-2021-23663 affects Sey Project Sey. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-23663?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2021-23663 published?

CVE-2021-23663 was published on 2021-12-10 and last updated on 2026-06-17.

CVE-2021-23663

CVE-2021-23663 is a medium-severity vulnerability in Sey Project Sey 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-1321.

Key facts

Severity: Medium (CVSS 3.x base score 6.5)
CVSS v2: 7.5
EPSS exploit prediction: 1% (64th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-1321
Affected product: Sey Project Sey
Published: 2021-12-10
Last modified: 2026-06-17

Description

All versions of package sey are vulnerable to Prototype Pollution via the deepmerge() function.

Frequently asked questions

What is CVE-2021-23663?: All versions of package sey are vulnerable to Prototype Pollution via the deepmerge() function.
How severe is CVE-2021-23663?: CVE-2021-23663 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity low, and availability low.
Is CVE-2021-23663 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (64th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-23663?: CVE-2021-23663 affects Sey Project Sey. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-23663?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2021-23663 published?: CVE-2021-23663 was published on 2021-12-10 and last updated on 2026-06-17.

References

https://snyk.io/vuln/SNYK-JS-SEY-1727592

Affected products (1)

cpe:2.3:a:sey_project:sey:*:*:*:*:*:node.js:*:*

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