CVE-2021-4188

Name: CVE-2021-4188
Creator: NVD / NIST
Published: 2021-12-30T07:15:06.527+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

HIGHCVSS 7.5/10EPSS 0.84%

Last modified Jun 17, 2026

CVE-2021-4188 is a high-severity vulnerability rated 7.5/10 on the CVSS scale. mruby is vulnerable to NULL Pointer Dereference. EPSS estimates a 0.84% chance of exploitation in the next 30 days.

Description

mruby is vulnerable to NULL Pointer Dereference

Metrics

CVSS 3.1

7.5/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS Probability

0.84%

53.1th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Vendor	Product	Versions
Mruby	Mruby	<= 3.0.0

References

https://github.com/mruby/mruby/commit/27d1e0132a0804581dca28df042e7047fd27eaa8Patch, Third Party Advisory
https://huntr.dev/bounties/78533fb9-f3e0-47c2-86dc-d1f96d5bea28Exploit, Patch, Third Party Advisory
https://github.com/mruby/mruby/commit/27d1e0132a0804581dca28df042e7047fd27eaa8Patch, Third Party Advisory
https://huntr.dev/bounties/78533fb9-f3e0-47c2-86dc-d1f96d5bea28Exploit, Patch, Third Party Advisory

Timeline

Published: Dec 30, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-4188?

mruby is vulnerable to NULL Pointer Dereference

How severe is CVE-2021-4188?

CVE-2021-4188 has a CVSS score of 7.5/10 (HIGH severity). The EPSS model estimates a 0.84% probability of exploitation in the next 30 days.

How do I fix CVE-2021-4188?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2021-4188?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST