CVE-2021-3520: LZ4 Project LZ4

Critical severity, CVSS 9.8. EPSS: 3.2% chance of exploitation in the next 30 days.

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.

Affected products

• LZ4 Project LZ4: from 1.8.3, before 1.9.4 (fixed in 1.9.4)
• Netapp Active Iq Unified Manager: affected versions not specified
• Netapp Cloud Backup: affected versions not specified
• Netapp Ontap Select Deploy Administration Utility: affected versions not specified
• Oracle Communications Cloud Native Core Policy: version 1.14.0 only
• Oracle ZFS Storage Appliance Kit: version 8.8 only
• Splunk Universal Forwarder: from 8.2.0, before 8.2.12 (fixed in 8.2.12); from 9.0.0, before 9.0.6 (fixed in 9.0.6); version 9.1.0 only

Published 2021-06-02. Last modified 2026-10-08.