Critical 9.8Published Mar 12, 2021

CVE-2021-20231A flaw was found in gnutls.

Updated under an hour ago (Oct 27, 2026, 8:30 AM ET)

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It affects Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP and 7 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

A flaw was found in gnutls. A use after free issue in client sending key_share extension may lead to memory corruption and other consequences.

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): CWE-416
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: redhat
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 gnutls gnu:gnutls	from 3.6.3 before 3.7.1	NVD
redhat enterprise_linux redhat:enterprise_linux	8.0	NVD
fedoraproject fedora fedoraproject:fedora	34	NVD
netapp active_iq_unified_manager netapp:active_iq_unified_manager	all versions	NVD
netapp e-series_performance_analyzer netapp:e-series_performance_analyzer	all versions	NVD

References

References

https://bugzilla.redhat.com/show_bug.cgi?id=1922276	x-refsource-misc, issue-tracking, patch, third-party-advisory
https://www.gnutls.org/security-new.html#GNUTLS-SA-2021-03-10	x-refsource-misc, exploit, vendor-advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/OSLAE6PP33A7VYRYMYMUVB3U6B26GZER/	vendor-advisory, x-refsource-fedora
https://lists.apache.org/thread.html/r5f88bed447742fcc5c47bf1c7be965ef450131914a6e1f85feba2779%40%3Cissues.spark.apache.org%3E	mailing-list, x-refsource-mlist
https://security.netapp.com/advisory/ntap-20210416-0005/	x-refsource-confirm, third-party-advisory
https://lists.apache.org/thread.html/rcd70a4c88a47a75fd2d5f3ffb7cee8c2a18c713320bd90fdcb57495f%40%3Cissues.spark.apache.org%3E	mailing-list, x-refsource-mlist
https://lists.apache.org/thread.html/r5d4001031e7790d8c6396c499522b4ed2aab782da87b1a14184793bb%40%3Cissues.spark.apache.org%3E	mailing-list, x-refsource-mlist
https://lists.apache.org/thread.html/r9cbc69e57276413788e90a6ee16c7c034ea4258d31935b70db2bd158%40%3Cissues.spark.apache.org%3E	mailing-list, x-refsource-mlist
https://lists.apache.org/thread.html/rfd5273d72d244178441e6904a2f2b41a3268f569e8092ea0b3b2bb20%40%3Cissues.spark.apache.org%3E	mailing-list, x-refsource-mlist
https://lists.apache.org/thread.html/rf5e1256d870193def4a82ad89ab95e63943a313b5ff0d81aa87e4532%40%3Cissues.spark.apache.org%3E	mailing-list, x-refsource-mlist
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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.