CVE-2021-25945: Prototype pollution vulnerability in 'js-extend' versions 0.0.1 through 1.0.1 allows attacker to cause a denia

Q: How do I fix CVE-2021-25945?

js-extend: upgrade to newer than 1.0.1. Exact commands for each OS are on this page.

Q: Is CVE-2021-25945 being exploited?

CVE-2021-25945 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-2021-25945 affect?

CVE-2021-25945 affects js-extend. Severity is critical (CVSS 9.8). Prototype pollution vulnerability in 'js-extend' versions 0.0.1 through 1.0.1 allows attacker to cause a denial of service and may lead to remote code execution.

Q: How urgent is CVE-2021-25945?

Priority 66/100. Critical severity; Public exploit reference; Remotely exploitable, no login, no user action

This week

CRITICAL 9.8REMOTEUPGRADE

CVE-2021-25945 is a critical-severity flaw (CVSS 9.8) affecting js-extend. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Prototype pollution vulnerability in 'js-extend' versions 0.0.1 through 1.0.1 allows attacker to cause a denial of service and may lead to remote code execution.

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	9.8 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	3.0% (top 13%)
CISA exploited list	No
Weakness	CWE-1321
Published	2021-05-26
Last modified	2026-06-17

Publisher (CNA): Mend · Vendor: js-extend project

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

Am I affected?

Timeline

2021-05-26 15:15 UTCPublished CVE record published
2026-06-17 03:42 UTCUpdated Record last modified

js-extend project js-extend UPGRADE

Affected: >= 0.0.1 and <= 1.0.1

Fixed in: newer than 1.0.1

Safe to downgrade to: a release before 0.0.1

1. Check installed version

npm ls js-extend

2. UPGRADE to newer than 1.0.1

npm install js-extend@">1.0.1"

3. If no update is available yet, DOWNGRADE to a release before 0.0.1

npm view js-extend versions npm install js-extend@"<0.0.1"

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

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-2021-25945?

js-extend: upgrade to newer than 1.0.1. Exact commands for each OS are on this page.

Is CVE-2021-25945 being exploited?

CVE-2021-25945 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-2021-25945 affect?

CVE-2021-25945 affects js-extend. Severity is critical (CVSS 9.8). Prototype pollution vulnerability in 'js-extend' versions 0.0.1 through 1.0.1 allows attacker to cause a denial of service and may lead to remote code execution.

How urgent is CVE-2021-25945?

Priority 66/100. Critical severity; Public exploit reference; Remotely exploitable, no login, no user action

References

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