CVE-2025-61939
Columbiaweather Weather Microserver Firmware ≤ MS_4.1_14142
Raw vector
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/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:XSummary
CVE-2025-61939 is a high-severity Improper Restriction of Communication Channel to Intended Endpoints (CWE-923) vulnerability in Columbiaweather Weather Microserver Firmware. Its CVSS base score is 8.7 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Adversary-in-the-Middle (T1557); ranked at the 16th 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 IA-3 (Device Identification and Authentication) and SC-23 (Session Authenticity) — 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-2025-61939 affects MicroServer, where an unused function can initiate a reverse SSH connection to a vendor-registered domain without mutual authentication. This vulnerability, associated with CWE-923 (Omission of Security-relevant Information), was published on 2026-01-07 and carries a CVSS v3.1 base score of 8.8 (AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H), indicating high severity due to its potential for significant impact on confidentiality, integrity, and availability.
An attacker on the local network with administrative access to the web server and the ability to manipulate DNS responses can exploit this issue by redirecting the reverse SSH connection to an attacker-controlled device. This allows the attacker to achieve high-impact outcomes, including potential remote code execution or unauthorized access, leveraging the lack of mutual authentication.
Mitigation guidance is provided in CISA ICS Advisory ICSA-26-006-01, available at https://www.cisa.gov/news-events/ics-advisories/icsa-26-006-01, along with the corresponding CSAF JSON file at https://github.com/cisagov/CSAF/blob/develop/csaf_files/OT/white/2026/icsa-26-006-01.json. Security practitioners should consult these resources for vendor-specific patches, workarounds, or configuration changes.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-1172
Vulnerability Data
An unused function in MicroServer can start a reverse SSH connection to a vendor registered domain, without mutual authentication. An attacker on the local network with admin access to the web server, and the ability to manipulate DNS responses, can…
more
redirect the SSH connection to an attacker controlled device.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise Techniques
CVEs Like This One
Affected Assets
Mitigating Controls
Control response
—
—
- 5 hardening rules · 3 OS baselines
V8.4.1V10.5.5V12.3.5
Mitigating Controls (NIST 800-53 r5) AI
Requires unique identification and authentication of devices before establishing a communications session.
Enforces authenticity of communication sessions so the system only exchanges data with verified intended endpoints.
Protects transmitted information with cryptographic integrity mechanisms that implicitly verify endpoint identity.
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.
Network segmentation and access controls directly enforce communication only with intended endpoints.
Authenticating services/hardware directly prevents communication with unintended endpoints.
Data-in-transit protections commonly include certificate-based endpoint authentication to ensure correct peers.
Documenting authorized flows helps define intended endpoints but does not enforce channel restrictions at runtime.
Protecting identity assertions supports endpoint verification but is narrower than channel restriction.
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.
Secure authentication mechanisms ensure the product communicates only with intended, authenticated endpoints.
Network security controls directly enforce endpoint validation and channel restrictions.
Security of network services includes authentication of endpoints and service-to-service channel protection.
Network segregation reduces exposure but does not itself validate specific endpoints.
Cryptography can protect channels but does not guarantee correct endpoint identity without additional controls.
Application security requirements may specify endpoint validation but do not implement it.
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 (2 rules)
- V-248827 OL 8 must not have the rsh-server package installed. prevents CWE-923
- V-248823 OL 8 must not have the telnet-server package installed. prevents CWE-923
RHEL 7 (1 rule)
- V-204442 The Red Hat Enterprise Linux operating system must not have the rsh-server package installed. prevents CWE-923
RHEL 8 (2 rules)
- V-230492 RHEL 8 must not have the rsh-server package installed. prevents CWE-923
- V-230487 RHEL 8 must not have the telnet-server package installed. prevents CWE-923