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Vulnerabilities/CVE-2021-3520Public Intelligence Dossier
Source: lz4 project · Limited verification•Last verified: •Collection Degraded
CVE-2021-3520Unknown / EvaluatingCRITICAL (raw)CVSS 9.8CWE-190

There's a flaw in lz4

Published: 02 Jun 2021•Last updated: 14 Oct 2026, 03:47 PM IST•Source identifier: secalert@redhat.com
Dossier completeness: source-provided sections 2 / 3 · rule guidance available. Missing source facts count as incomplete.
Official source
CISA KEV catalog
Unknown
KEV status was not determined.
CVSS score
9.8CRITICAL (raw)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Metric sourcenvd@nist.gov
EPSS probability
3.4%0.034
Percentile89th
Weakness type
CWE-190
CWE-787
Remediation
Patch status unknown
No fixed version or KB recorded

Why It Matters

Analysis dossier

Why It Matters

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.

SOC priority

High Severity / Review

Actively exploited

Unknown

Publicly disclosed

Unknown

Risk basis: SOC ecosystem technology relevance; CRITICAL severity; Critical CVSS without confirmed KEV exploitation

Affected Products & Remediation

7 source-backed products
Affected products and versions (source)
  • lz4 project lz4 · >= 1.8.3 < 1.9.4 · NVD CPE · Source
  • netapp active iq unified manager · version range not provided by source · NVD CPE · Source
  • netapp cloud backup · version range not provided by source · NVD CPE · Source
  • netapp ontap select deploy administration utility · version range not provided by source · NVD CPE · Source
  • oracle communications cloud native core policy · 1.14.0 · NVD CPE · Source
  • oracle zfs storage appliance kit · 8.8 · NVD CPE · Source
  • splunk universal forwarder · >= 8.2.0 < 8.2.12; >= 9.0.0 < 9.0.6; 9.1.0 · NVD CPE · Source
Recorded patch / KBNot provided by source

Vendor or catalog guidance (source)

Not provided by source

Known exploitation (source facts)

Only what a source states. Unknown means no source has said either way; it is not "not exploited".

CISA KEV
Unknown
Exploited (source statement)
Unknown
Publicly disclosed (source)
Unknown

Suggested hunting (rule-based inference)

SecOps Signal recommendation (rule-based inference). These steps are hunting hypotheses from the vulnerability class; they do not state or imply that exploitation occurred here or anywhere.

Matched network-unauthenticated (CVSS AV:N, CVSS PR:N, CVSS UI:N)

Exposure

  1. Identify devices reporting this CVE and note which expose the affected service to untrusted networks.Telemetry: DeviceTvmSoftwareVulnerabilities · A network-reachable, no-privilege vector makes internet-facing instances the first exposure question. · Rule network-unauthenticated

Exploitation evidence

  1. Review inbound connections to the affected service from unexpected sources since the advisory date.Telemetry: DeviceNetworkEvents · Hunting hypothesis from the CVSS vector; it does not show that exploitation occurred. · Rule network-unauthenticated

Response

  1. Confirm the source-stated update is installed and the CVE is no longer reported.Telemetry: DeviceTvmSoftwareVulnerabilities · A follow-up inventory check verifies remediation. · Rule network-unauthenticated

CISA KEV Record

CISA KEV status was not determined for this record.

Change History & Source Data

— No recorded material change

CNA / source
secalert@redhat.com
Record status · verification
UPDATED · NVD API
CPE
cpe:2.3:a:lz4_project:lz4:*:*:*:*:*:*:*:*, cpe:2.3:a:netapp:active_iq_unified_manager:-:*:*:*:*:vmware_vsphere:*:*, cpe:2.3:a:netapp:cloud_backup:-:*:*:*:*:*:*:*, cpe:2.3:a:netapp:ontap_select_deploy_administration_utility:-:*:*:*:*:*:*:*, cpe:2.3:a:oracle:communications_cloud_native_core_policy:1.14.0:*:*:*:*:*:*:*, cpe:2.3:a:oracle:zfs_storage_appliance_kit:8.8:*:*:*:*:*:*:*, cpe:2.3:a:splunk:universal_forwarder:*:*:*:*:*:*:*:*, cpe:2.3:a:splunk:universal_forwarder:9.1.0:*:*:*:*:*:*:*

Evidence & Provenance

3 public sources
bugzilla.redhat.comSource recordnvd.nist.govSource recordsecurity.netapp.comSource record

Linked by the query's stored exact CVE association. Review required tables and validation status before use.

Detection Hunting Query
Target: DeviceTvmSoftwareVulnerabilities•Defender XDR
Detect endpoints exposed to CVE-2021-3520
Purpose: Exposure assessment (Category: Exposure Check)Why linked: Query metadata names CVE-2021-3520
DeviceTvmSoftwareVulnerabilities| where CveId == "CVE-2021-3520"| project DeviceId, DeviceName, OSPlatform, OSVersion, SoftwareVendor, SoftwareName, SoftwareVersion, CveId, VulnerabilitySeverityLevel, RecommendedSecurityUpdate, RecommendedSecurityUpdateId| sort by VulnerabilitySeverityLevel desc
Schema Checked · Not runtime validatedSource: SecOps Signal deterministic template · Limited verificationStatic screening: Passed structure and schema checks; tenant execution is not verified.
Open KQL Library

Correlated briefings

— No published briefing references this CVE

SecOps Signal surfaces public advisory facts only. A missing value means the source has not published it, not that your environment is unaffected. No tenant inventory is connected.