Critical 9.8Published May 24, 2021

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

Updated under an hour ago (Oct 27, 2026, 5:23 AM ET)

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It affects Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP and 15 other products. Add what you run to find out whether that includes you.

No exploitation reported and no EPSS estimate yet.

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Every CVE for Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP

Exploited in the last 30 days

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: 9.8 CRITICAL (v3.1, NVD)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Weakness (CWE): Not given
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: mitre
NVD analysis: Modified
Record last updated: Oct 14, 2026
First seen by InfoSec Signals: Oct 14, 2026

Affected products

Affected products

Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP siemens:simatic_s7_1500_cpu_1518_4_pn_dp_mfp (from the name)	from V3.1.0 before V3.1.5	CISA ADP
Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP siemens:simatic_s7_1500_cpu_1518f_4_pn_dp_mfp (from the name)	from V3.1.0 before V3.1.5	CISA ADP
Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP siemens:siplus_s7_1500_cpu_1518_4_pn_dp_mfp (from the name)	from V3.1.0 before V3.1.5	CISA ADP
gnu glibc gnu:glibc	2.32; 2.33	NVD
fedoraproject fedora fedoraproject:fedora	33; 34	NVD
netapp cloud_backup netapp:cloud_backup	all versions	NVD
netapp e-series_santricity_os_controller netapp:e-series_santricity_os_controller	from 11.0 through 11.70.1	NVD
netapp solidfire_baseboard_management_controller_firmware netapp:solidfire_baseboard_management_controller_firmware	all versions	NVD
netapp h300s_firmware netapp:h300s_firmware	all versions	NVD
netapp h500s_firmware netapp:h500s_firmware	all versions	NVD
1–10 of 16

References

References

https://sourceware.org/bugzilla/show_bug.cgi?id=27896	exploit, issue-tracking, third-party-advisory
https://sourceware.org/bugzilla/show_bug.cgi?id=27896#c1	issue-tracking
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/RBUUWUGXVILQXVWEOU7N42ICHPJNAEUP/	vendor-advisory
https://security.netapp.com/advisory/ntap-20210629-0005/	third-party-advisory
https://security.gentoo.org/glsa/202107-07	vendor-advisory, third-party-advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/KJYYIMDDYOHTP2PORLABTOHYQYYREZDD/	vendor-advisory
https://lists.debian.org/debian-lts-announce/2022/10/msg00021.html	mailing-list, third-party-advisory
https://cert-portal.siemens.com/productcert/html/ssa-398330.html
https://cert-portal.siemens.com/productcert/html/ssa-831302.html

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.