CVE-2021-33574

CRITICALNVD 9.89.8—
EchelonGraph scoreMEDIUM confidence

Score 9.8 from GitHub Security Advisory (severity: CRITICAL) published 2022-05-24. NVD baseline CVSS 9.8; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
Trending — 3 sources updated this week
9.8
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS: 3%CVSS: 9.8Exploit: NoneExposed: 0

A fix is available — apply it.

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.

CVSS v3
9.8
EG Score
9.8(medium)
EG Risk
50(Track)
EG Risk 50/100SSVC: Track

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity98% × 45%
Exploitation3% × 40%
Automatability30% × 15%
Action: Routine — remediate on your standard cadence.
EPSS
85.5%
KEV
Not listed

Published

May 25, 2021

Last Modified

November 21, 2024

Advisory Details (7)

Auto-updated Jun 10, 2026
Patch available.
generic

[SECURITY] Fedora 34 Update: glibc-2.33-16.fc34 - package-announce - Fedora mailing-lists

https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/RBUUWUGXVILQXVWEOU7N42ICHPJNAEUP/
generic

[SECURITY] Fedora 33 Update: glibc-2.32-8.fc33 - package-announce - Fedora mailing-lists

https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/KJYYIMDDYOHTP2PORLABTOHYQYYREZDD/
generic Patch Available

[SECURITY] [DLA 3152-1] glibc security update

https://lists.debian.org/debian-lts-announce/2022/10/msg00021.html
generic

27896 – (CVE-2021-33574) mq_notify does not handle separately allocated thread attributes (CVE-2021-33574)

https://sourceware.org/bugzilla/show_bug.cgi?id=27896#c1
generic

27896 – (CVE-2021-33574) mq_notify does not handle separately allocated thread attributes (CVE-2021-33574)

https://sourceware.org/bugzilla/show_bug.cgi?id=27896
generic

NetApp Product Security

https://security.netapp.com/advisory/ntap-20210629-0005/
generic

glibc: Multiple vulnerabilities (GLSA 202107-07) — Gentoo security

https://security.gentoo.org/glsa/202107-07

Vendor Advisories for CVE-2021-33574(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Patch Availability(1)

Vendor / EcosystemFixed in / PatchReleasedSource
redhatglibc-0:2.28-164.el82021-11-09redhat

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Additional Vendor Advisories

(1)

Vendors that published advisories for this CVE beyond the curated set above. Broader coverage but minimal per-row detail — click through for the original advisory.

Data Freshness Timeline

(refreshed 15× in last 7d / 47× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

Showing the most recent 100 of 102 total refreshes for this CVE.

  1. 2026-07-23 02:01 UTCEG score recompute
  2. 2026-07-22 22:48 UTCEG score recompute
  3. 2026-07-22 14:06 UTCEPSS rescore
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  1. 2026-07-07 13:43 UTCEPSS rescore
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  9. 2026-07-01 02:48 UTCOSV refresh
  10. 2026-06-30 23:20 UTCEPSS rescore
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  38. 2026-06-13 05:13 UTCOSV refresh
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  71. 2026-05-26 16:08 UTCEG score recompute
  72. 2026-05-26 16:08 UTCVendor advisory
  73. 2026-05-26 16:07 UTCGHSA enrichment
  74. 2026-05-26 13:42 UTCEPSS rescore
  75. 2026-05-26 07:17 UTCEPSS rescore

Related CVEs(same vendor + same CWE)

Frequently asked(5)

What is CVE-2021-33574?
CVE-2021-33574 is a critical vulnerability published on May 25, 2021. 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…
When was CVE-2021-33574 disclosed?
CVE-2021-33574 was first published in the National Vulnerability Database on May 25, 2021, with the most recent update on November 21, 2024. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2021-33574 actively exploited?
CVE-2021-33574 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 85.5% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2021-33574?
CVE-2021-33574 has a CVSS v3 base score of 9.8 (NVD).
How do I remediate CVE-2021-33574?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2021-33574, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

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