CVE-2021-3420

Name: CVE-2021-3420
Creator: NVD / NIST
Published: 2021-03-05T21:15:13.437+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

CRITICALCVSS 9.8/10EPSS 2.10%

Last modified Jun 17, 2026

CVE-2021-3420 is a critical-severity vulnerability rated 9.8/10 on the CVSS scale. A flaw was found in newlib in versions prior to 4.0.0. Improper overflow validation in the memory allocation functions mEMALIGn, pvALLOc, nano_memalign, nano_valloc, nano_pvalloc could case an integer overflow, leading to an allocation of a small buffer and then to a heap-based buffer overflow.. EPSS estimates a 2.10% chance of exploitation in the next 30 days.

Description

A flaw was found in newlib in versions prior to 4.0.0. Improper overflow validation in the memory allocation functions mEMALIGn, pvALLOc, nano_memalign, nano_valloc, nano_pvalloc could case an integer overflow, leading to an allocation of a small buffer and then to a heap-based buffer overflow.

Metrics

CVSS 3.1

9.8/10

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

EPSS Probability

2.10%

79.4th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-190

Affected Software

Vendor	Product	Versions
Newlib Project	Newlib	< 4.0.0
Fedoraproject	Fedora	32
Fedoraproject	Fedora	33
Fedoraproject	Fedora	34

References

Timeline

Published: Mar 5, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-3420?

How severe is CVE-2021-3420?

CVE-2021-3420 has a CVSS score of 9.8/10 (CRITICAL severity). The EPSS model estimates a 2.10% probability of exploitation in the next 30 days.

How do I fix CVE-2021-3420?

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-2021-3420?

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

Scan your code now

Source: NVD / NIST