What is CVE-2021-42581?

CVE-2021-42581 is a critical-severity vulnerability in Ramdajs Ramda, classified under Improperly Controlled Modification of Object Prototype Attributes (Prototype Pollution). CVSS score: 9.1/10. Published 2022-05-10.

How severe is CVE-2021-42581?

Critical severity. CVSS v3 base score is 9.1 out of 10.

Prototype Pollution in Ramdajs Ramda

CVE-2021-42581

Prototype poisoning in function mapObjIndexed in Ramda 0.27.0 and earlier allows attackers to compromise integrity or availability of application via supplying a crafted object (that contains an own property "__proto__") as an argument to the function. NOTE: the vendor disputes this because the observed behavior only means that a user can create objects that the user didn't know would contain custom prototypes

Vulnerability class: Prototype Pollution

Published 2022-05-10 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 9.1 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H.

EPSS exploit prediction

EPSS: 0.014 (72.0th percentile), scored 2026-10-24.

Low probability of exploitation in the next 30 days, but still tracked. 72nd percentile — 72.0% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.014 · newest: 0.014 · change: +0.000

Affected products

Ramdajs Ramda

Weakness classification (CWE)

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

References

github.com/ramda/ramda/pull/3192 (Patch, Third Party Advisory, Issue Tracking)
jsfiddle.net/3pomzw5g/2/ (Exploit, Third Party Advisory)

Frequently asked questions

What is CVE-2021-42581?: CVE-2021-42581 is a critical-severity vulnerability in Ramdajs Ramda, classified under Improperly Controlled Modification of Object Prototype Attributes (Prototype Pollution). CVSS score: 9.1/10. Published 2022-05-10.
How severe is CVE-2021-42581?: Critical severity. CVSS v3 base score is 9.1 out of 10.