Raw vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:HSummary
CVE-2025-52376 is a critical-severity Improper Authentication (CWE-287) vulnerability. Its CVSS base score is 9.8 (Critical).
Operationally, exploitation aligns with the MITRE ATT&CK technique Unsecured Credentials (T1552); ranked in the top 5% of CVEs by exploit likelihood; it is not currently listed in the CISA KEV catalog.
The strongest mitigations our analysis identified map to IA-2 (Identification and Authentication (Organizational Users)) and IA-3 (Device Identification and Authentication) — see the control section below for these in your framework.
Deeper analysis AI-assisted summary
Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.
CVE-2025-52376 is an authentication bypass vulnerability affecting the /web/um_open_telnet.cgi endpoint in Nexxt Solutions NCM-X1800 Mesh Router firmware versions UV1.2.7 and below. The flaw allows remote attackers to enable the Telnet service without any authentication, circumventing built-in security controls. Once enabled, the Telnet server exposes hard-coded credentials that grant administrative shell access. The vulnerability 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) and is associated with CWE-287 (Improper Authentication) and CWE-798 (Use of Hard-coded Credentials).
Any unauthenticated remote attacker with network access to the vulnerable router can exploit this issue by sending a crafted request to the /web/um_open_telnet.cgi endpoint. This triggers the Telnet service to start, after which the attacker can connect using the hard-coded credentials to obtain full administrative privileges. Successful exploitation enables arbitrary command execution on the device, potentially leading to complete compromise, including data theft, configuration manipulation, or use as a pivot point in the network.
Public proof-of-concept exploits for CVE-2025-52376 are available on GitHub, including a detailed writeup documenting the attack methodology. No official vendor advisories or patches are referenced in available sources.
OWASP Top 10 for Web (2025)
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2025-21439
Vulnerability Data
An authentication bypass vulnerability in the /web/um_open_telnet.cgi endpoint in Nexxt Solutions NCM-X1800 Mesh Router firmware UV1.2.7 and below, allowing an attacker to remotely enable the Telnet service without authentication, bypassing security controls. The Telnet server is then accessible with hard-coded…
more
credentials, allowing attackers to gain administrative shell access and execute arbitrary commands on the device.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise Techniques
CVEs Like This One
Affected Assets
Mitigating Controls
Control response
—
—
- 8 hardening rules · 5 OS baselines
V6.4.4V6.5.4V6.5.5V6.5.7
Mitigating Controls (NIST 800-53 r5) AI
Mandates unique identification and authentication of organizational users before access, directly stopping improper authentication.
Requires unique identification and authentication of devices before establishing connections, preventing unauthenticated device claims.
Mandates unique identification and authentication of non-organizational users, directly addressing the weakness for external actors.
Manages authenticators with verification and secure distribution, reducing opportunities for improper authentication.
Cryptographic key management mandates proper establishment and handling instead of embedding keys in code.
Enforces access only after approved authorizations, which presupposes correct authentication has occurred.
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 directly enforces authentication mechanisms that eliminate most improper-authentication defects, yet CWE-287 spans additional vectors (missing checks, flawed protocols, session handling) that one control does not fully close.
PR.AA-04 directly enables verification of identity assertions (mostly preventing CWE-287 in that scope) yet leaves many other authentication failure modes unaddressed (only partial prevention overall).
PR.AA-01 supplies and governs credentials/tokens that authentication relies on, removing some weak-credential cases, yet leaves verification logic, missing checks, and protocol flaws untouched.
PR.AA-02 ensures valid enrollment and unique credential binding, which reduces some improper-auth risks at issuance time but leaves runtime claim verification untouched, so each direction only partially addresses the other.
PR.PS-01 can enforce auth-related settings via hardened baselines and default reviews, blocking some config-based instances of CWE-287, yet leaves code-level auth flaws untouched so neither direction reaches mostly.
Patching/maintenance can remediate some known auth vulnerabilities after deployment (partial forward) but does not address the design or implementation of authentication logic itself (none reverse).
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.
Requiring authentication methods whose strength matches the sensitivity of the data and mandating multi-factor authentication directly blocks attempts to access resources without proving identity.
Verifying user identity before issuing replacement credentials and forcing changes after compromise reduces the likelihood that authentication bypass can be achieved through stolen or weak credentials.
Mandating segregated approval and oversight for non-human identities reduces the chance that weak or orphaned credentials can be exploited for unauthorized authentication.
Education on secure configuration practices discourages technical staff from embedding or relying on hard-coded credentials in systems and applications.
Requiring authentication mechanisms and technical parameters for secure connections ensures that network services verify user identity before granting access, preventing exploitation of missing or weak authentication.
Secure key-generation, distribution and storage procedures reduce the likelihood that hard-coded or default cryptographic keys will be introduced or left unprotected.
Hardening callouts derived
Configuration rules from DISA STIG baselines that bear on weaknesses of the type cited by this CVE. Each rule is shown with the relationship its mapping actually records, against the CWE it was authored against. Derived via CVE→CWE over `controls_xwalks` (authoritative rows only; rows rated `none` are excluded).
Oracle Linux 8 (1 rule)
- V-248827 OL 8 must not have the rsh-server package installed. prevents CWE-287
RHEL 7 (3 rules)
- V-204425 The Red Hat Enterprise Linux operating system must be configured so that the SSH daemon does not allow authentication using an empty password. prevents CWE-287
- V-204442 The Red Hat Enterprise Linux operating system must not have the rsh-server package installed. prevents CWE-287
- V-204424 The Red Hat Enterprise Linux operating system must not allow accounts configured with blank or null passwords. prevents CWE-287
RHEL 8 (1 rule)
- V-230492 RHEL 8 must not have the rsh-server package installed. prevents CWE-287
Ubuntu 22.04 (1 rule)
- V-260470 Ubuntu 22.04 LTS, when booted, must require authentication upon booting into single-user and maintenance modes. prevents CWE-287
Ubuntu 24.04 (2 rules)
- V-270675 Ubuntu 24.04 LTS when booted must require authentication upon booting into single-user and maintenance modes. prevents CWE-287
- V-270714 Ubuntu 24.04 LTS must not allow accounts configured in Pluggable Authentication Modules (PAM) with blank or null passwords. prevents CWE-287