Nettle
CVE-2021-20305
HIGH
Vulnerability Assessment
| Weakness |
CWE
OWASP Top 10:2025
A04:2025 - Cryptographic Failures
ASVS 5.0
V11 - Cryptography Approved algorithm selection
|
| Impact | CVSS score of 8.1 (HIGH). Attack characteristics: network attack vector, high complexity, no privileges required, no user interaction not required. |
| Exploit ScenarioDerived | This vulnerability can be exploited remotely over the network. Successful exploitation could compromise the high-severity affected system. |
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Alert meAnalysisAI
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. Rated high severity (CVSS 8.1), this vulnerability is remotely exploitable, no authentication required.
RemediationAI
A vendor patch is available. Apply the latest security update as soon as possible. Apply vendor patches when available. Implement network segmentation and monitoring as interim mitigations.
Affects your stack
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Technical ContextAI · show details
This vulnerability is classified under CWE-327. 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. Affected products include: Nettle Project Nettle, Fedoraproject Fedora, Redhat Enterprise Linux, Netapp Active Iq Unified Manager, Netapp Ontap Select Deploy Administration Utility. Version information: before 3.7.2.
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- Exploit and PoC references, threat intelligence from 22 sources
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Severity by source
AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Primary rating from NVD · only source for this CVE.
CVSS VectorNVD
DescriptionNVD
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.
Threat Intelligence Overview
NVD
CVE.org
EPSS
VulDB
How this decision was reached
The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.
What every action level means
SSVC AssessmentENISA
Priority Score
Attack Technique
Denial of Service attacks render applications or systems unavailable by overwhelming resources or triggering failure conditions.
Affected Products (CPE)NVD
The ecc_256_modp function in ecc-256.c in Nettle before 3.2 does not properly handle carry propagation and produces inco
x86_64/ecc-384-modp.asm in Nettle before 3.2 does not properly handle carry propagation and produces incorrect output in
The ecc_256_modq function in ecc-256.c in Nettle before 3.2 does not properly handle carry propagation and produces inco
The OCB feature in libnettle in Nettle 3.9 before 3.9.1 allows memory corruption. Rated critical severity (CVSS 9.8), th
The RSA and DSA decryption code in Nettle makes it easier for attackers to discover private keys via a cache side channe
A flaw was found in the way nettle's RSA decryption functions handled specially crafted ciphertext. Rated high severity
A Bleichenbacher type side-channel based padding oracle attack was found in the way nettle handles endian conversion of
GitHub PoC
Exploit-DB