CVE-2021-42581: Prototype poisoning in function mapObjIndexed in Ramda 0.27.0 and earlier allows attackers to compromise integ

Q: How do I fix CVE-2021-42581?

ramda: upgrade to newer than 0.27.0. Exact commands for each OS are on this page.

Q: Is CVE-2021-42581 being exploited?

CVE-2021-42581 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2021-42581 affect?

CVE-2021-42581 affects ramda. Severity is critical (CVSS 9.1). 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 t

Q: How urgent is CVE-2021-42581?

Priority 60/100. Critical severity; Public exploit reference; Remotely exploitable, no login, no user action

This week

CRITICAL 9.1REMOTEUPGRADE

CVE-2021-42581 is a critical-severity flaw (CVSS 9.1) affecting ramda. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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

Why this priority

Critical severity
Public exploit reference
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	9.1 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	1.4% (top 28%)
CISA exploited list	No
Weakness	CWE-1321
Published	2022-05-10
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: ramdajs

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2022-05-10 11:15 UTCPublished CVE record published
2026-06-17 04:09 UTCUpdated Record last modified

ramdajs ramda UPGRADE

Affected: <= 0.27.0

Fixed in: newer than 0.27.0

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy ramda || rpm -q ramda || ramda --version

2. UPGRADE to newer than 0.27.0 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade ramda

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade ramda

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2021-42581?

ramda: upgrade to newer than 0.27.0. Exact commands for each OS are on this page.

Is CVE-2021-42581 being exploited?

CVE-2021-42581 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2021-42581 affect?

CVE-2021-42581 affects ramda. Severity is critical (CVSS 9.1). 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 t

How urgent is CVE-2021-42581?

Priority 60/100. Critical severity; Public exploit reference; Remotely exploitable, no login, no user action

References

← Back to latest CVEs