CVE-2019-20149: ctorName in index.js in kind-of v6.0.2 allows external user input to overwrite certain internal attributes via

This week

HIGH 7.5REMOTEDOWNGRADE

CVE-2019-20149 is a high-severity flaw (CVSS 7.5) affecting kind-of. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

ctorName in index.js in kind-of v6.0.2 allows external user input to overwrite certain internal attributes via a conflicting name, as demonstrated by 'constructor': {'name':'Symbol'}. Hence, a crafted payload can overwrite this builtin attribute to manipulate the type detection result.

Why this priority

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

No fix is published yet: follow the downgrade or mitigation steps.

Risk facts

CVSS score	7.5 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	2.3% (top 16%)
CISA exploited list	No
Weakness	CWE-668
Published	2019-12-30
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: kind-of project

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

Am I affected?

Timeline

2019-12-30 19:15 UTCPublished CVE record published
2026-06-17 02:30 UTCUpdated Record last modified

kind-of project kind-of DOWNGRADE

Affected: 6.0.2

Fixed in: no fixed release known

Safe to downgrade to: a release before 6.0.2

1. Check installed version

apt-cache policy kind-of || rpm -q kind-of || kind-of --version

2. No fixed release: DOWNGRADE to a release before 6.0.2 (Debian / Ubuntu)

apt-cache madison kind-of sudo apt install kind-of=<VERSION_BEFORE_6.0.2> sudo apt-mark hold kind-of

2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list kind-of sudo dnf downgrade kind-of-<VERSION_BEFORE_6.0.2> sudo dnf versionlock add kind-of

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-2019-20149?

kind-of: downgrade or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2019-20149 being exploited?

CVE-2019-20149 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-2019-20149 affect?

CVE-2019-20149 affects kind-of. Severity is high (CVSS 7.5). ctorName in index.js in kind-of v6.0.2 allows external user input to overwrite certain internal attributes via a conflicting name, as demonstrated by 'constructor': {'name':'Symbol'}. Hence, a crafted payload can overwrite this builtin attr

How urgent is CVE-2019-20149?

Priority 57/100. High severity; Public exploit reference; Remotely exploitable, no login, no user action

References

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