CVE-2021-33574

Exp

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.

Published: 2021-05-25 Last update: 2024-11-21 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2021-33574 is rated High Exploit Risk (86.7/100): CVSS Critical severity, with medium exploitation likelihood (EPSS 2.90%). 1 public exploit reference(s) are indexed (Exploit-DB). EPSS rose +2.75% over the last day, indicating growing attacker interest. Public exploits are available—assess exposure, apply mitigations, and prioritize patching.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Public exploit references (Exploit-DB) for CVE-2021-33574

EDB-ID Source Kind Published Link
— nvd_ref exploit_tag Exploit-DB ↗

Exploit prediction scoring system (EPSS) score for CVE-2021-33574

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 0.15% 2.90% +2.75%
2 2025-11-21 1.11% 0.15% -0.96%
3 2025-11-18 — 1.11% —

Full EPSS history (22 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2021-33574

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
9.8 3.1 CRITICAL
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 5.9 [email protected]
7.5 2.0 HIGH
AV:N/AC:L/Au:N/C:P/I:P/A:P Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:L)
Exploitation conditions are straightforward and predictable.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:P)
Partial confidentiality impact.
Integrity impact (I:P)
Partial integrity impact.
Availability impact (A:P)
Partial availability impact.
 10.0 6.4 [email protected]

Weakness enumeration for CVE-2021-33574

OS Trackers for CVE-2021-33574

vendor priority summary link
debian not yet assigned CVE-2021-33574 not yet assigned priority: Debian including 1 source packages (glibc), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. https://security-tracker.debian.org/tracker/CVE-2021-33574
gentoo normal CVE-2021-33574: 1 GLSA(s) (202107-07), 1 atom(s) (sys-libs/glibc); latest impact normal. https://bugs.gentoo.org/buglist.cgi?quicksearch=CVE-2021-33574
redhat low — https://access.redhat.com/security/cve/CVE-2021-33574
suse medium CVE-2021-33574 severity moderate: SUSE including 860 source package names (0.1.0:glibc-2.26-13.59.1, 0.1.75:glibc-2.26-13.59.1, …), 2372 product×package rows across 430 product lines (Container bci/bci-base-fips, Container bci/bci-busybox, … (430 product lines)): Fixed 2218, Known Affected 154. https://www.suse.com/security/cve/CVE-2021-33574/
ubuntu low CVE-2021-33574 low priority: Ubuntu including 2 source packages (eglibc, glibc), 18 status rows across 9 suites (bionic, focal, groovy, hirsute, impish, jammy, trusty, upstream, xenial): DNE 8, ignored 6, not-affected 2, needs-triage 1, released 1. https://ubuntu.com/security/CVE-2021-33574

Affected software / configurations for CVE-2021-33574

Vendor Product Version Raw CPE
gnu glibc 2.32 cpe:2.3:a:gnu:glibc:2.32:*:*:*:*:*:*:*
gnu glibc 2.33 cpe:2.3:a:gnu:glibc:2.33:*:*:*:*:*:*:*
fedoraproject fedora 33 cpe:2.3:o:fedoraproject:fedora:33:*:*:*:*:*:*:*
fedoraproject fedora 34 cpe:2.3:o:fedoraproject:fedora:34:*:*:*:*:*:*:*
netapp cloud_backup — cpe:2.3:a:netapp:cloud_backup:-:*:*:*:*:*:*:*
netapp e-series_santricity_os_controller >= 11.0, <= 11.70.1 cpe:2.3:a:netapp:e-series_santricity_os_controller:*:*:*:*:*:*:*:*
netapp solidfire_baseboard_management_controller_firmware — cpe:2.3:o:netapp:solidfire_baseboard_management_controller_firmware:-:*:*:*:*:*:*:*
netapp h300s_firmware — cpe:2.3:o:netapp:h300s_firmware:-:*:*:*:*:*:*:*
netapp h500s_firmware — cpe:2.3:o:netapp:h500s_firmware:-:*:*:*:*:*:*:*
netapp h700s_firmware — cpe:2.3:o:netapp:h700s_firmware:-:*:*:*:*:*:*:*
netapp h300e_firmware — cpe:2.3:o:netapp:h300e_firmware:-:*:*:*:*:*:*:*
netapp h500e_firmware — cpe:2.3:o:netapp:h500e_firmware:-:*:*:*:*:*:*:*
netapp h700e_firmware — cpe:2.3:o:netapp:h700e_firmware:-:*:*:*:*:*:*:*
netapp h410s_firmware — cpe:2.3:o:netapp:h410s_firmware:-:*:*:*:*:*:*:*
debian debian_linux 10.0 cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:*

References for CVE-2021-33574

cvelogic Threat Intelligence