CVE-2021-3520

Name: CVE-2021-3520
Creator: NVD / NIST
Published: 2021-06-02T13:15:13.17+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

CRITICALCVSS 9.8/10EPSS 3.22%

Last modified Jun 17, 2026

CVE-2021-3520 is a critical-severity vulnerability rated 9.8/10 on the CVSS scale. There's a flaw in lz4. An attacker who submits a crafted file to an application linked with lz4 may be able to trigger an integer overflow, leading to calling of memmove() on a negative size argument, causing an out-of-bounds write and/or a crash. EPSS estimates a 3.22% chance of exploitation in the next 30 days.

Description

There's a flaw in lz4. An attacker who submits a crafted file to an application linked with lz4 may be able to trigger an integer overflow, leading to calling of memmove() on a negative size argument, causing an out-of-bounds write and/or a crash. The greatest impact of this flaw is to availability, with some potential impact to confidentiality and integrity as well.

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

3.22%

86.6th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Vendor	Product	Versions
Lz4 Project	Lz4	>= 1.8.3, < 1.9.4
Netapp	Active Iq Unified Manager	All versions
Netapp	Cloud Backup	All versions
Netapp	Ontap Select Deploy Administration Utility	All versions
Oracle	Communications Cloud Native Core Policy	1.14.0
Oracle	Zfs Storage Appliance Kit	8.8
Splunk	Universal Forwarder	>= 8.2.0, < 8.2.12
Splunk	Universal Forwarder	>= 9.0.0, < 9.0.6
Splunk	Universal Forwarder	9.1.0

References

https://bugzilla.redhat.com/show_bug.cgi?id=1954559Issue Tracking, Patch, Third Party Advisory
https://security.netapp.com/advisory/ntap-20211104-0005/Third Party Advisory
https://www.oracle.com//security-alerts/cpujul2021.htmlPatch, Third Party Advisory
https://www.oracle.com/security-alerts/cpuapr2022.htmlPatch, Third Party Advisory
https://www.oracle.com/security-alerts/cpuoct2021.htmlPatch, Third Party Advisory
https://bugzilla.redhat.com/show_bug.cgi?id=1954559Issue Tracking, Patch, Third Party Advisory
https://security.netapp.com/advisory/ntap-20211104-0005/Third Party Advisory
https://www.oracle.com//security-alerts/cpujul2021.htmlPatch, Third Party Advisory
https://www.oracle.com/security-alerts/cpuapr2022.htmlPatch, Third Party Advisory
https://www.oracle.com/security-alerts/cpuoct2021.htmlPatch, Third Party Advisory

Timeline

Published: Jun 2, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-3520?

How severe is CVE-2021-3520?

CVE-2021-3520 has a CVSS score of 9.8/10 (CRITICAL severity). The EPSS model estimates a 3.22% probability of exploitation in the next 30 days.

How do I fix CVE-2021-3520?

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-2021-3520?

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

Scan your code now

Source: NVD / NIST