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Vulnerabilities/CVE-2021-20305Public Intelligence Dossier
Source: nettle project · Limited verification•Last verified: •Collection Degraded
CVE-2021-20305Unknown / EvaluatingHIGH (raw)CVSS 8.1CWE-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

Published: 06 Apr 2021•Last updated: 14 Oct 2026, 04:46 PM IST•Source identifier: secalert@redhat.com
Dossier completeness: source-provided sections 2 / 3 · rule guidance available. Missing source facts count as incomplete.
Official source
CISA KEV catalog
Unknown
KEV status was not determined.
CVSS score
8.1HIGH (raw)
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Metric sourcenvd@nist.gov
EPSS probability
1.7%0.017
Percentile77th
Weakness type
CWE-327
CWE-787
Remediation
Patch status unknown
No fixed version or KB recorded

Why It Matters

Analysis dossier

Why It Matters

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.

SOC priority

High

Actively exploited

Unknown

Publicly disclosed

Unknown

Risk basis: SOC ecosystem technology relevance; HIGH severity; No confirmed exploitation signal in current enrichment

Affected Products & Remediation

6 source-backed products
Affected products and versions (source)
  • nettle project nettle · < 3.7.2 · NVD CPE · Source
  • fedoraproject fedora · 33 · NVD CPE · Source
  • redhat enterprise linux · 7.0; 8.0 · NVD CPE · Source
  • netapp active iq unified manager · version range not provided by source · NVD CPE · Source
  • netapp ontap select deploy administration utility · version range not provided by source · NVD CPE · Source
  • debian debian linux · 9.0; 10.0 · NVD CPE · Source
Recorded patch / KBNot provided by source

Vendor or catalog guidance (source)

Not provided by source

Known exploitation (source facts)

Only what a source states. Unknown means no source has said either way; it is not "not exploited".

CISA KEV
Unknown
Exploited (source statement)
Unknown
Publicly disclosed (source)
Unknown

Suggested hunting (rule-based inference)

SecOps Signal recommendation (rule-based inference). These steps are hunting hypotheses from the vulnerability class; they do not state or imply that exploitation occurred here or anywhere.

Matched network-unauthenticated (CVSS AV:N, CVSS PR:N, CVSS UI:N)

Exposure

  1. Identify devices reporting this CVE and note which expose the affected service to untrusted networks.Telemetry: DeviceTvmSoftwareVulnerabilities · A network-reachable, no-privilege vector makes internet-facing instances the first exposure question. · Rule network-unauthenticated

Exploitation evidence

  1. Review inbound connections to the affected service from unexpected sources since the advisory date.Telemetry: DeviceNetworkEvents · Hunting hypothesis from the CVSS vector; it does not show that exploitation occurred. · Rule network-unauthenticated

Response

  1. Confirm the source-stated update is installed and the CVE is no longer reported.Telemetry: DeviceTvmSoftwareVulnerabilities · A follow-up inventory check verifies remediation. · Rule network-unauthenticated

CISA KEV Record

CISA KEV status was not determined for this record.

Change History & Source Data

— No recorded material change

CNA / source
secalert@redhat.com
Record status · verification
UPDATED · NVD API
CPE
cpe:2.3:a:nettle_project:nettle:*:*:*:*:*:*:*:*, cpe:2.3:o:fedoraproject:fedora:33:*:*:*:*:*:*:*, cpe:2.3:o:redhat:enterprise_linux:7.0:*:*:*:*:*:*:*, cpe:2.3:o:redhat:enterprise_linux:8.0:*:*:*:*:*:*:*, cpe:2.3:a:netapp:active_iq_unified_manager:-:*:*:*:*:vmware_vsphere:*:*, cpe:2.3:a:netapp:ontap_select_deploy_administration_utility:-:*:*:*:*:*:*:*, cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*, cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:*

Evidence & Provenance

3 public sources
bugzilla.redhat.comSource recordnvd.nist.govSource recordlists.debian.orgSource record

Linked by the query's stored exact CVE association. Review required tables and validation status before use.

Detection Hunting Query
Target: DeviceTvmSoftwareVulnerabilities•Defender XDR
Detect endpoints exposed to CVE-2021-20305
Purpose: Exposure assessment (Category: Exposure Check)Why linked: Query metadata names CVE-2021-20305
DeviceTvmSoftwareVulnerabilities| where CveId == "CVE-2021-20305"| project DeviceId, DeviceName, OSPlatform, OSVersion, SoftwareVendor, SoftwareName, SoftwareVersion, CveId, VulnerabilitySeverityLevel, RecommendedSecurityUpdate, RecommendedSecurityUpdateId| sort by VulnerabilitySeverityLevel desc
Schema Checked · Not runtime validatedSource: SecOps Signal deterministic template · Limited verificationStatic screening: Passed structure and schema checks; tenant execution is not verified.
Open KQL Library

Correlated briefings

— No published briefing references this CVE

SecOps Signal surfaces public advisory facts only. A missing value means the source has not published it, not that your environment is unaffected. No tenant inventory is connected.