CVE-2025-40836

Critical

Published: 25 September 2025

Published

25 September 2025

Modified

02 October 2025

KEV Added

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Patch

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CVSS Score 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS Score 0.0016 36.4th percentile

Risk Priority 20 60% EPSS · 20% KEV · 20% CVSS

Summary

CVE-2025-40836 is a critical-severity Improper Input Validation (CWE-20) vulnerability in Ericsson Indoor Connect 8855 Firmware. Its CVSS base score is 9.8 (Critical).

Operationally, exploitation aligns with the MITRE ATT&CK technique Exploit Public-Facing Application (T1190); ranked at the 36.4th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.

The strongest mitigations our analysis identified are NIST 800-53 SI-10 (Information Input Validation) and SI-2 (Flaw Remediation).

Threat & Defense at a Glance

What attackers do: exploitation maps to Exploit Public-Facing Application (T1190) and 1 other technique. What defenders deploy: see the NIST 800-53 controls recommended below.

Threat & Defense Details

Mitigating Controls (NIST 800-53 r5)AI

SI-10 Information Input Validation good match

prevent

SI-10 directly enforces proper input validation mechanisms at system interfaces, preventing exploitation of the improper input validation vulnerability (CWE-20).

SI-2 Flaw Remediation good match

prevent

SI-2 requires timely identification, reporting, and correction of flaws like this CVE, mitigating it through patching as recommended by the vendor.

AC-6 Least Privilege partial match

prevent

AC-6 enforces least privilege, limiting the impact of arbitrary command execution even if input validation fails and privileges are escalated.

MITRE ATT&CK Enterprise TechniquesAI

T1190 Exploit Public-Facing Application Initial Access

Adversaries may attempt to exploit a weakness in an Internet-facing host or system to initially access a network.

attack.mitre.org →

T1068 Exploitation for Privilege Escalation Privilege Escalation

Adversaries may exploit software vulnerabilities in an attempt to elevate privileges.

attack.mitre.org →

Why these techniques?

Improper input validation on a network-exposed device enables unauthenticated remote arbitrary command execution with privilege escalation, directly mapping to T1190 (public-facing app exploitation) and T1068 (priv esc via exploitation).

Confidence: HIGH · MITRE ATT&CK Enterprise v18.1

NVD Description

Ericsson Indoor Connect 8855 contains an improper input validation vulnerability which if exploited can allow an attacker to execute commands with escalated privileges.

Deeper analysisAI

CVE-2025-40836 is an improper input validation vulnerability (CWE-20) in Ericsson Indoor Connect 8855. Published on 2025-09-25, the issue carries a CVSS v3.1 base score of 9.8 (AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H), reflecting its critical severity due to the potential for remote exploitation with high impacts on confidentiality, integrity, and availability.

An unauthenticated attacker with network access to the affected device can exploit this vulnerability through a low-complexity attack requiring no user interaction. Successful exploitation allows the attacker to execute arbitrary commands with escalated privileges on the device.

Ericsson's PSIRT advisory at https://www.ericsson.com/en/about-us/security/psirt/e2025-09-25 provides further details on the vulnerability and recommended mitigations.