CVE-2017-9481 — The Comcast firmware on Cisco DPC3939 (firmware version dpc3939-P20-18-v303r2042

The Comcast firmware on Cisco DPC3939 (firmware version dpc3939-P20-18-v303r20421746-170221a-CMCST) devices allows remote attackers to obtain unintended access to the Network Processor (NP) 169.254/16 IP network by adding a routing-table entry that specifies the LAN IP address as

01What is this vulnerability?

The Comcast firmware on Cisco DPC3939 (firmware version dpc3939-P20-18-v303r20421746-170221a-CMCST) devices allows remote attackers to obtain unintended access to the Network Processor (NP) 169.254/16 IP network by adding a routing-table entry that specifies the LAN IP address as the router for that network.

02Affected products

No structured affected-product list available — see references below for vendor advisories.

03Active exploitation status

Not currently listed on the CISA Known Exploited Vulnerabilities (KEV) catalog. EPSS is the best forward-looking signal — see the EPSS row above.

04Recommended remediation

• Patch to a fixed version listed in the vendor advisory (see references below).
• Mitigate with WAF rules, network egress filters, or feature flags where the patch is not yet available.
• Hunt historical logs for exploitation indicators — see Detection signatures below.

05Technical details

For the full vendor write-up, exploit chains, and reference implementations, see the references list in section 09.

06Detection signatures

Ask SARA in chat to draft a starting detection for this CVE in your stack of choice.

07Related CVEs

No directly-cited follow-up CVEs in the KB record for this advisory. The references list in section 09 carries the vendor cross-references.

08Timeline

• Published: 2017-07-31T03:29:00.410
• Last modified: 2026-05-13T00:24:29.033

09References

• github.com — https://github.com/BastilleResearch/CableTap/blob/master/doc/advisories/bastille…
• github.com — https://github.com/BastilleResearch/CableTap/blob/master/doc/advisories/bastille…