CVE-2021-20305

HighCVSS 8.1/10Last modified Oct 14, 2026

Description

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.

Metrics

CVSS 3.1 8.1/10CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

Weakness enumeration

CWE-327CWE-787

Affected software

VendorProductVersions
n/anettlenettle 3.7.2
SiemensSIMATIC S7-1500 CPU 1518-4 PN/DP MFP>= V3.1.0, < V3.1.5
SiemensSIMATIC S7-1500 CPU 1518-4 PN/DP MFP>= V3.1.0, < V3.1.5
SiemensSIMATIC S7-1500 CPU 1518F-4 PN/DP MFP>= V3.1.0, < V3.1.5
SiemensSIMATIC S7-1500 CPU 1518F-4 PN/DP MFP>= V3.1.0, < V3.1.5
SiemensSIPLUS S7-1500 CPU 1518-4 PN/DP MFP>= V3.1.0, < V3.1.5

References

Timeline

Published
Apr 5, 2021
Last modified
Oct 14, 2026
NVD status
Modified

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CVE-2021-20305: High severity, CVSS 8.1 | Vulnix