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CVE Record

CVE-2021-3520: There's a flaw in lz4.

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.

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysismoderate

Security readout for executives and security teams

Plain-English summary

CVE-2021-3520 is a flaw in lz4 where a specially crafted file can make an application using lz4 corrupt memory or crash. The clearest business risk is service disruption. The provided sources do not establish active exploitation or provide a universal fixed version.

Executive priority

Handle as a targeted remediation item for systems that process external files. It is not confirmed as actively exploited in the provided sources, but memory corruption and crash risk justify inventory and vendor-guided updates.

Technical view

The issue is an integer overflow in lz4, reported against lz4-1.8.3. A crafted file processed by an application linked with lz4 may lead to memmove() receiving a negative size argument, causing out-of-bounds write and/or crash. It is categorized as CWE-190.

Likely exposure

Exposure is most likely in applications, appliances, or packaged products that use lz4 and process untrusted compressed files. The bundle names lz4-1.8.3 and references downstream vendor advisories from Red Hat, Oracle, and NetApp, so inventory should include both direct libraries and vendor-managed products.

Exploitation context

The source bundle describes a crafted-file attack path, but KEV is false and no cited source states active exploitation. Treat exploit status as unconfirmed from the provided evidence.

Researcher notes

Evidence is limited to the CVE description and referenced vendor advisories. No CVSS vector, universal patch level, or exploit confirmation is included in the bundle. Avoid broad claims beyond lz4-1.8.3 and vendor-specific applicability.

Mitigation direction

  • Check lz4 and downstream vendor advisories for applicable fixed versions.
  • Update affected vendor products according to Red Hat, Oracle, NetApp, or other supplier guidance.
  • Prioritize systems that process untrusted or external files using lz4.
  • Reduce exposure of file-processing services until vendor remediation is confirmed.

Validation and detection

  • Identify installed lz4 versions and products bundling lz4.
  • Confirm whether lz4-1.8.3 exists in production, build images, or appliances.
  • Review file-processing applications for links to lz4 libraries.
  • Check vendor advisory applicability for Oracle, NetApp, Red Hat, and other supported platforms.
Prepared
Confidence
medium
Sources
7

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.

ATT&CK lookup starting points

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cwe · low confidence lookup

CWE-190: Exact CWE lookup

Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.

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cve · low confidence lookup

CVE-2021-3520 mapping review

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Vulnerability profileCVE Program record
Severity
Unknown
CVSS
Not scored
Known Exploited
No
Published
Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

0CVSS vectors
0Timeline events
0ADP providers
6Source links

CVSS and timeline data

No CVSS vectors or timeline events were available in the normalized CVE source material.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
n/alz4lz4-1.8.3Listed
Weakness

CWE details

CWE-190

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.