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Vulnerabilities/CVE-2021-3518Public Intelligence Dossier
Source: xmlsoft · Limited verification•Last verified: •Collection Degraded
CVE-2021-3518Unknown / EvaluatingHIGH (raw)CVSS 8.8CWE-416

There's a flaw in libxml2 in versions before 2.9.11

Published: 18 May 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
8.8HIGH (raw)
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Metric sourcenvd@nist.gov
EPSS probability
21.9%0.219
Percentile98th
Weakness type
CWE-416
No further CWE recorded
Remediation
Patch status unknown
No fixed version or KB recorded

Why It Matters

Analysis dossier

Why It Matters

There's a flaw in libxml2 in versions before 2.9.11. An attacker who is able to submit a crafted file to be processed by an application linked with libxml2 could trigger a use-after-free. The greatest impact from this flaw is to confidentiality, integrity, and availability.

SOC priority

High

Actively exploited

Unknown

Publicly disclosed

Unknown

Risk basis: Microsoft or Microsoft-managed product relevance; HIGH severity; No confirmed exploitation signal in current enrichment

Affected Products & Remediation

18 source-backed products
Affected products and versions (source)
  • xmlsoft libxml2 · < 2.9.11 · NVD CPE · Source
  • debian debian linux · 9.0 · NVD CPE · Source
  • redhat jboss core services · version range not provided by source · NVD CPE · Source
  • redhat enterprise linux · 8.0 · NVD CPE · Source
  • fedoraproject fedora · 33; 34 · NVD CPE · Source
  • netapp active iq unified manager · version range not provided by source · NVD CPE · Source
  • netapp clustered data ontap · version range not provided by source · NVD CPE · Source
  • netapp clustered data ontap antivirus connector · version range not provided by source · NVD CPE · Source
  • netapp manageability software development kit · version range not provided by source · NVD CPE · Source
  • netapp ontap select deploy administration utility · version range not provided by source · NVD CPE · Source
  • netapp snapdrive · version range not provided by source · NVD CPE · Source
  • netapp hci h410c firmware · version range not provided by source · NVD CPE · Source
  • oracle communications cloud native core network function cloud native environment · 1.10.0 · NVD CPE · Source
  • oracle enterprise manager base platform · 13.4.0.0; 13.5.0.0 · NVD CPE · Source
  • oracle enterprise manager ops center · 12.4.0.0 · NVD CPE · Source
  • oracle mysql workbench · <= 8.0.26 · NVD CPE · Source
  • oracle peoplesoft enterprise peopletools · 8.58 · NVD CPE · Source
  • oracle real user experience insight · 13.4.1.0; 13.5.1.0 · NVD CPE · Source
NVD applicability prerequisites: cpe:2.3:h:netapp:hci_h410c:-:*:*:*:*:*:*:*. These are conditions, not proof that an environment is exposed or unaffected.
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 user-interaction-client (CVSS AV:N, CVSS UI:R)

Exposure

  1. Identify endpoints reporting this CVE, especially those used for email and web browsing.Telemetry: DeviceTvmSoftwareVulnerabilities · A network vector that needs user interaction points at user-facing client software. · Rule user-interaction-client

Exploitation evidence

  1. Review unusual child processes started by the affected client application on affected endpoints.Telemetry: DeviceProcessEvents · Hunting hypothesis from the CVSS vector; it does not show that exploitation occurred. · Rule user-interaction-client

Response

  1. Confirm the source-stated update on affected endpoints.Telemetry: DeviceTvmSoftwareVulnerabilities · A follow-up inventory check verifies remediation. · Rule user-interaction-client

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:xmlsoft:libxml2:*:*:*:*:*:*:*:*, cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*, cpe:2.3:a:redhat:jboss_core_services:-:*:*:*:*:*:*:*, cpe:2.3:o:redhat:enterprise_linux:8.0:*:*:*:*:*:*:*, cpe:2.3:o:fedoraproject:fedora:33:*:*:*:*:*:*:*, cpe:2.3:o:fedoraproject:fedora:34:*:*:*:*:*:*:*, cpe:2.3:a:netapp:active_iq_unified_manager:-:*:*:*:*:vmware_vsphere:*:*, cpe:2.3:a:netapp:clustered_data_ontap:-:*:*:*:*:*:*:*, cpe:2.3:a:netapp:clustered_data_ontap_antivirus_connector:-:*:*:*:*:*:*:*, cpe:2.3:a:netapp:manageability_software_development_kit:-:*:*:*:*:*:*:*

Evidence & Provenance

3 public sources
bugzilla.redhat.comSource recordnvd.nist.govSource recordlists.apache.orgSource 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-2021-3518
Purpose: Exposure assessment (Category: Exposure Check)Why linked: Query metadata names CVE-2021-3518
DeviceTvmSoftwareVulnerabilities| where CveId == "CVE-2021-3518"| 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.