CVE intelligence and bounded remediation

CVE-2020-29138 — Sagemcom F@St 3486 Router Firmware security vulnerability

Medium CVSS 5.3

Incorrect Access Control in the configuration backup path in SAGEMCOM F@ST3486 NET DOCSIS 3.0, software NET_4.109.0, allows remote unauthenticated users to download the router configuration file via the /backupsettings.conf URI, when any valid session is running.

Severity
Medium
CVSS
5.3 (3.1)
Published
2020-11-27
CISA KEV
Not currently listed
Ecosystem
operating-system
Weaknesses
CWE-306

Affected products

  • sagemcom / f@st_3486_router_firmware / 4.109.0

Matched remediation archetype

Authentication bypass and missing authentication

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Check exposure

  • Map every affected endpoint and protocol path, including alternate ports, legacy routes, recovery flows, service accounts, and machine-to-machine access.
  • Confirm which deployments enable the affected authentication mode and whether the interface is reachable from untrusted networks.
  • Review session, token, credential, and proxy trust configuration without attempting account takeover.

Remediate safely

  • Apply the supported fix and centralize fail-closed authentication before protected request handling.
  • Remove default or embedded credentials, rotate affected secrets and sessions, and bind authentication decisions to the intended audience and channel.
  • Add negative tests for alternate routes, malformed or absent credentials, recovery flows, and proxy-derived identity.

Authoritative sources

Complete CVE record and remediation plan

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