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CVE Record

CVE-2021-33574: The mq_notify function in the GNU C Library (aka glibc) versions 2.32 and 2.33 has a use-after-free.

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.

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysismoderate

Security readout for executives and security teams

Plain-English summary

This flaw is in glibc, a core system library used by many Linux systems. In affected glibc versions 2.32 and 2.33, a message-queue notification path can use memory after the caller has freed it. The documented impact is application crash, with possible unspecified other impact.

Executive priority

Handle through standard Linux patch management with added attention to message-queue-heavy workloads. Urgency is moderate: the known impact is application crash, no active exploitation is cited, and the affected versions are specific, but glibc is foundational and widely reused.

Technical view

CVE-2021-33574 is a use-after-free in glibc mq_notify. The function may use the notification thread attributes object supplied through struct sigevent after caller-controlled lifetime has ended. The source bundle identifies glibc 2.32 and 2.33 and describes denial of service through process crash, with other impact not specified.

Likely exposure

Exposure is most likely on systems running glibc 2.32 or 2.33 where applications use POSIX message queue notification via mq_notify. Fedora, Gentoo, Debian LTS, and NetApp references indicate downstream vendor handling, but the bundle does not enumerate all affected packages or platforms.

Exploitation context

The bundle does not show CISA KEV listing or evidence of active exploitation. Public references describe the vulnerability and downstream advisories, not real-world exploitation. Treat this as a stability and availability risk unless vendor-specific guidance states broader impact.

Researcher notes

Evidence is strongest for the vulnerable component and affected upstream versions. The bundle lacks CVSS, CWE mapping, exploit maturity, and full downstream fixed-version detail. Avoid assuming code execution; the cited description only states denial of service and possible unspecified other impact.

Mitigation direction

  • Inventory systems and containers for glibc 2.32 or 2.33.
  • Apply the relevant operating system or vendor glibc security update.
  • Prioritize systems running applications that use POSIX message queues.
  • Check downstream advisories for platform-specific fixed package versions.
  • Restart affected services after glibc updates where required.

Validation and detection

  • Confirm installed glibc version on each in-scope host or image.
  • Review vendor advisory status for the exact distribution release.
  • Identify applications using mq_notify or POSIX message queue notification.
  • Verify patched package installation through package manager records.
  • Run normal service health checks after updating glibc.
Prepared
Confidence
medium
Sources
8

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

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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
7Source 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/an/an/aListed
Weakness

CWE details

No CWE listed

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