Cyber Resilience

CVE-2026-31847

High

Published: 23 March 2026

Published
23 March 2026
Modified
26 March 2026
KEV Added
—
Patch
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CVSS Score v4 8.5 CVSS:4.0/AV:A/AC:L/AT:N/PR:H/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 0.0042 33.9th percentile
Risk Priority 55 floored blend · peak EPSS

Summary

CVE-2026-31847 is a high-severity Hidden Functionality (CWE-912) vulnerability in Amazonaws (inferred from references). Its CVSS base score is 8.5 (High).

Operationally, exploitation aligns with the MITRE ATT&CK technique External Remote Services (T1133); ranked at the 33.9th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.

EU & UK References

Vulnerability details

Hidden functionality in the /goform/setSysTools endpoint in Nexxt Solutions Nebula 300+ firmware through version 12.01.01.37 allows remote enablement of a Telnet service. By sending a crafted POST request with parameters such as telnetManageEn=true and telnetPwd, an authenticated attacker can activate…

more

a Telnet service on port 23. This exposes a privileged diagnostic interface that is not intended for external access and can be used to interact with the underlying system.

CWE(s)
CWE-912

Related Threats

MITRE ATT&CK Enterprise TechniquesAI

T1133 External Remote Services Persistence
Adversaries may leverage external-facing remote services to initially access and/or persist within a network.
attack.mitre.org →
Why these techniques?

Vulnerability directly enables activation of unauthorized Telnet remote service for external access/persistence on the device.

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

Affected Assets

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

Mitigating Controls

Likely Mitigating Controls AI

Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.

CM-8 System Component Inventory
addresses: CWE-912

Documenting every system component at the required granularity and reviewing the inventory detects or prevents hidden functionality from remaining undetected.

CP-10 System Recovery and Reconstitution
addresses: CWE-912

Recovery eliminates hidden functionality or backdoors introduced during compromise.

PM-30 Supply Chain Risk Management Strategy
addresses: CWE-912

Policy requires supplier transparency and testing to detect hidden functionality or backdoors inserted in the supply chain.

PS-2 Position Risk Designation
addresses: CWE-912

Screening high-risk technical positions lowers the probability that hidden functionality or backdoors will be added by authorized personnel.

RA-10 Threat Hunting
addresses: CWE-912

Hunting identifies hidden functionality used for persistence or evasion after initial compromise.

RA-6 Technical Surveillance Countermeasures Survey
addresses: CWE-912

TSCM surveys discover and eliminate hidden surveillance functionality that would otherwise remain undetected in the environment.

SA-10 Developer Configuration Management
addresses: CWE-912

Change control, approval gates, and flaw tracking force hidden functionality to be either documented or discovered and removed.

SA-12 Supply Chain Protection
addresses: CWE-912

Vetting and integrity controls during acquisition reduce the likelihood of hidden backdoors or malicious functionality introduced by suppliers.

References