CVE intelligence and bounded remediation

CVE-2017-9488 — Cisco Dpc3939 Firmware security vulnerability

High CVSS 8.8

The Comcast firmware on Cisco DPC3939 (firmware version dpc3939-P20-18-v303r20421746-170221a-CMCST) and DPC3941T (firmware version DPC3941_2.5s3_PROD_sey) devices allows remote attackers to access the web UI by establishing a session to the wan0 WAN IPv6 address and then entering unspecified hardcoded credentials. This wan0 interface cannot be accessed from the public Internet.

Severity
High
CVSS
8.8 (3.0)
Published
2017-07-31
CISA KEV
Not currently listed
Ecosystem
operating-system
Weaknesses
CWE-798

Affected products

  • cisco / dpc3939_firmware / dpc3939-p20-18-v303r20421746-170221a-cmcst
  • cisco / dpc3941t_firmware / dpc3941_2.5s3_prod_sey

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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