What is CVE-2025-57323?

CVE-2025-57323 is a high-severity vulnerability in Regularjs Mpregular, classified under Improperly Controlled Modification of Object Prototype Attributes (Prototype Pollution). CVSS score: 7.5/10. Published 2025-09-24.

How severe is CVE-2025-57323?

High severity. CVSS v3 base score is 7.5 out of 10.

Prototype Pollution in Regularjs Mpregular

CVE-2025-57323

mpregular is a package that provides a small program development framework based on RegularJS. A Prototype Pollution vulnerability in the mp.addEventHandler function of mpregular version 0.2.0 and before allows attackers to inject properties on Object.prototype via supplying a crafted payload, causing denial of service (DoS) as the minimum consequence.

Vulnerability class: Prototype Pollution

Published 2025-09-24 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.

EPSS exploit prediction

EPSS: 0.004 (33.4th percentile), scored 2026-10-05.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 33rd percentile — 33.4% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.004 · newest: 0.004 · change: 0.000

Affected products

Regularjs Mpregular

Weakness classification (CWE)

CWE-1321 — Improperly Controlled Modification of Object Prototype Attributes (Prototype Pollution)

References

github.com/VulnSageAgent/PoCs/blob/main/JavaScript/prototype-pollution/mpregula… (Broken Link)
github.com/VulnSageAgent/PoCs/tree/main/JavaScript/prototype-pollution/CVE-2025… (Third Party Advisory)

Frequently asked questions

What is CVE-2025-57323?: CVE-2025-57323 is a high-severity vulnerability in Regularjs Mpregular, classified under Improperly Controlled Modification of Object Prototype Attributes (Prototype Pollution). CVSS score: 7.5/10. Published 2025-09-24.
How severe is CVE-2025-57323?: High severity. CVSS v3 base score is 7.5 out of 10.