High 8.1Published Apr 5, 2021

CVE-2021-20305A flaw was found in Nettle in versions before 3.7.2, where several Nettle signature verification functions (GOST DSA, EDDSA & ECDSA) result in the Elliptic Curve Cryptography point (ECC) multiply fun…

Updated under an hour ago (Oct 27, 2026, 10:10 PM ET)

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It affects Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP and 8 other products. Add what you run to find out whether that includes you.

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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 Nettle in versions before 3.7.2, where several Nettle signature verification functions (GOST DSA, EDDSA & ECDSA) result in the Elliptic Curve Cryptography point (ECC) multiply function being called with out-of-range scalers, possibly resulting in incorrect results. This flaw allows an attacker to force an invalid signature, causing an assertion failure or possible validation. The highest threat to this vulnerability is to confidentiality, integrity, as well as system availability.

CVSS: 8.1 HIGH (v3.1, NVD)CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Weakness (CWE): CWE-327
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
nettle_project nettle nettle_project:nettle	before 3.7.2	NVD
fedoraproject fedora fedoraproject:fedora	33	NVD
redhat enterprise_linux redhat:enterprise_linux	7.0; 8.0	NVD
netapp active_iq_unified_manager netapp:active_iq_unified_manager	all versions	NVD
netapp ontap_select_deploy_administration_utility netapp:ontap_select_deploy_administration_utility	all versions	NVD
debian debian_linux debian:debian_linux	9.0; 10.0	NVD

References

References

https://bugzilla.redhat.com/show_bug.cgi?id=1942533	x-refsource-misc, issue-tracking, patch, third-party-advisory
https://security.gentoo.org/glsa/202105-31	vendor-advisory, x-refsource-gentoo, third-party-advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/MQKWVVMAIDAJ7YAA3VVO32BHLDOH2E63/	vendor-advisory, x-refsource-fedora
https://www.debian.org/security/2021/dsa-4933	vendor-advisory, x-refsource-debian, third-party-advisory
https://lists.debian.org/debian-lts-announce/2021/09/msg00008.html	mailing-list, x-refsource-mlist, third-party-advisory
https://security.netapp.com/advisory/ntap-20211022-0002/	x-refsource-confirm, third-party-advisory
https://cert-portal.siemens.com/productcert/html/ssa-398330.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.