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Vulnerabilities/CVE-2021-33574Public Intelligence Dossier
Source: gnu · Limited verification•Last verified: •Collection Degraded
CVE-2021-33574Unknown / EvaluatingCRITICAL (raw)CVSS 9.8CWE-416

The mq_notify function in the GNU C Library (aka glibc) versions 2.32 and 2.33 has a use-after-free

Published: 26 May 2021•Last updated: 14 Oct 2026, 05:47 PM IST•Source identifier: cve@mitre.org
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
3.5%0.035
Percentile89th
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

The mq_notify function in the GNU C Library (aka glibc) versions 2.32 and 2.33 has a use-after-free. It may use the notification thread attributes object (passed through its struct sigevent parameter) after it has been freed by the caller, leading to a denial of service (application crash) or possibly unspecified other impact.

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

13 source-backed products
Affected products and versions (source)
  • gnu glibc · 2.32; 2.33 · NVD CPE · Source
  • fedoraproject fedora · 33; 34 · NVD CPE · Source
  • netapp cloud backup · version range not provided by source · NVD CPE · Source
  • netapp e-series santricity os controller · >= 11.0 <= 11.70.1 · NVD CPE · Source
  • netapp solidfire baseboard management controller firmware · version range not provided by source · NVD CPE · Source
  • netapp h300s firmware · version range not provided by source · NVD CPE · Source
  • netapp h500s firmware · version range not provided by source · NVD CPE · Source
  • netapp h700s firmware · version range not provided by source · NVD CPE · Source
  • netapp h300e firmware · version range not provided by source · NVD CPE · Source
  • netapp h500e firmware · version range not provided by source · NVD CPE · Source
  • netapp h700e firmware · version range not provided by source · NVD CPE · Source
  • netapp h410s firmware · version range not provided by source · NVD CPE · Source
  • debian debian linux · 10.0 · NVD CPE · Source
NVD applicability prerequisites: cpe:2.3:h:netapp:h300s:-:*:*:*:*:*:*:*, cpe:2.3:h:netapp:h500s:-:*:*:*:*:*:*:*, cpe:2.3:h:netapp:h700s:-:*:*:*:*:*:*:*, cpe:2.3:h:netapp:h300e:-:*:*:*:*:*:*:*, cpe:2.3:h:netapp:h500e:-:*:*:*:*:*:*:*, cpe:2.3:h:netapp:h700e:-:*:*:*:*:*:*:*, cpe:2.3:h:netapp:h410s:-:*:*:*:*:*:*:*. 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 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
cve@mitre.org
Record status · verification
UPDATED · NVD API
CPE
cpe:2.3:a:gnu:glibc:2.32:*:*:*:*:*:*:*, cpe:2.3:a:gnu:glibc:2.33:*:*:*:*:*:*:*, cpe:2.3:o:fedoraproject:fedora:33:*:*:*:*:*:*:*, cpe:2.3:o:fedoraproject:fedora:34:*:*:*:*:*:*:*, cpe:2.3:a:netapp:cloud_backup:-:*:*:*:*:*:*:*, cpe:2.3:a:netapp:e-series_santricity_os_controller:*:*:*:*:*:*:*:*, cpe:2.3:o:netapp:solidfire_baseboard_management_controller_firmware:-:*:*:*:*:*:*:*, cpe:2.3:o:netapp:h300s_firmware:-:*:*:*:*:*:*:*, cpe:2.3:h:netapp:h300s:-:*:*:*:*:*:*:*, cpe:2.3:o:netapp:h500s_firmware:-:*:*:*:*:*:*:*

Evidence & Provenance

3 public sources
nvd.nist.govSource recordlists.debian.orgSource recordlists.fedoraproject.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-2021-33574
Purpose: Exposure assessment (Category: Exposure Check)Why linked: Query metadata names CVE-2021-33574
DeviceTvmSoftwareVulnerabilities| where CveId == "CVE-2021-33574"| 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.