Cyber Resilience

CVE-2026-31851

Published
23 March 2026
Modified
26 March 2026
CVSS Score v4 7.7
Click a component to see what it means
Raw vectorCVSS:4.0/AV:A/AC:H/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
EPSS Score 0.0033 26th percentile
Risk Priority 55 floored blend · peak EPSS

Summary

CVE-2026-31851 is a high-severity Improper Restriction of Excessive Authentication Attempts (CWE-307) vulnerability in Amazonaws (inferred from references). Its CVSS base score is 7.7 (High).

Operationally, exploitation aligns with the MITRE ATT&CK technique Brute Force (T1110); ranked at the 26th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.

The strongest mitigations our analysis identified map to AC-3 (Access Enforcement) and AC-7 (Unsuccessful Logon Attempts) — see the control section below for these in your framework.

OWASP Top 10 for Web (2025)

A07:2025 Authentication Failures

EU & UK References

Vulnerability Data

Nexxt Solutions Nebula 300+ firmware through version 12.01.01.37 does not implement rate limiting or account lockout mechanisms on authentication interfaces. An attacker can perform unlimited authentication attempts against endpoints that rely on credential validation, enabling brute-force attacks to guess administrative…

more

credentials without restriction.

CWE(s)
CWE-307

Related Threats

MITRE ATT&CK Enterprise TechniquesAI

T1110 Brute Force Credential Access
Adversaries may use brute force techniques to gain access to accounts when passwords are unknown or when password hashes are obtained.
attack.mitre.org →
T1110.001 Password Guessing Credential Access
Adversaries with no prior knowledge of legitimate credentials within the system or environment may guess passwords to attempt access to accounts.
attack.mitre.org →
Why these techniques?

Missing rate limiting directly enables unlimited authentication attempts for brute-force credential guessing (T1110/T1110.001).

Confidence: HIGH · MITRE ATT&CK Enterprise v19.0

CVEs Like This One

CVE-2026-3329Shared CWE-307
CVE-2026-6853Shared CWE-307
CVE-2025-3129Shared CWE-307
CVE-2026-35623Shared CWE-307
CVE-2026-43914Shared CWE-307
CVE-2026-22616Shared CWE-307
CVE-2026-32295Shared CWE-307
CVE-2025-64310Shared CWE-307
CVE-2024-51476Shared CWE-307
CVE-2026-36959Shared CWE-307

Affected Assets

Amazonaws
—
inferred from references and description; NVD did not file a CPE for this CVE

Mitigating Controls

Control response

Prevent
Stop it (NIST 800-53)
  • AC-7 Unsuccessful Logon Attempts
  • AC-3 Access Enforcement
Detect
Catch it (NIST detect / respond)
  • SI-4 System Monitoring
Harden
Shrink the surface (DISA STIG)
  • 2 hardening rules · 1 OS baseline
Validate
Prove the fix (OWASP ASVS)

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Mitigating Controls (NIST 800-53 r5) AI

AC-7 Unsuccessful Logon Attempts good match
prevent

Directly enforces limits on consecutive unsuccessful logon attempts, implementing the account lockout missing from the Nebula firmware authentication endpoints.

AC-3 Access Enforcement good match
prevent

Requires the system to enforce authentication policies that would block unlimited credential attempts against the administrative interfaces.

SI-4 System Monitoring partial match
detect

Enables monitoring and alerting on excessive failed authentication events that indicate brute-force activity against the device.

Mitigating Controls (NIST CSF 2.0) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.

PR.AA-03 mostly match
prevents

Authentication enforcement directly includes lockout, throttling, and MFA policies that prevent brute-force attempts.

DE.CM-03 partial match
prevents

Behavioral monitoring of authentication activity can detect excessive failed attempts after they occur.

PR.PS-04 partial match
prevents

Generating auth logs enables later detection or forensics but does not itself restrict attempts.

Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.

A.8.5 Secure authentication partial match
prevents

CAPTCHA, account lock-out after repeated failures, and alerts on excessive attempts directly stop automated brute-force guessing of credentials.

References