Security readout for executives and security teams
Plain-English summary
This CVE describes a weakness in Comcast firmware for Cisco DPC3939 cable gateway devices. When the device operates in UI development mode, a remote attacker can write arbitrary data to a predictable temporary session-cookie file path. The sources do not provide CVSS, confirmed exploitation, or a vendor fix.
Executive priority
Treat this as a targeted legacy-device risk. Prioritize confirmation if Comcast-managed Cisco DPC3939 gateways remain in use. Urgency increases if management interfaces are remotely reachable or UI dev mode is enabled, but the available sources do not justify claiming active exploitation.
Technical view
CVE-2017-9485 affects Cisco DPC3939 devices running Comcast firmware dpc3939-P20-18-v303r20421746-170221a-CMCST. The flaw allows remote arbitrary data writes to a known /var/tmp/sess_* pathname when UI dev mode is active. Available source data does not describe impact chaining, authentication requirements, or remediation version.
Likely exposure
Exposure appears limited to environments still using the named Cisco DPC3939 Comcast firmware version, especially where UI dev mode is enabled or reachable remotely. The provided CVE metadata lists affected vendor and product as n/a, so asset confirmation is required.
Exploitation context
The source says remote attackers can write arbitrary data by leveraging UI dev mode. No provided source states active exploitation, and the bundle marks KEV as false. The available information does not include exploit maturity, public exploitation telemetry, or prerequisites beyond UI dev mode.
Researcher notes
The core issue is arbitrary data write to predictable /var/tmp/sess_* session-cookie paths under UI dev mode. The public bundle lacks CVSS, CWE, affected CPEs, authentication detail, patch status, and post-write impact analysis. Avoid assuming broader Cisco firmware exposure without vendor evidence.
Mitigation direction
- Inventory Cisco DPC3939 devices and confirm firmware version.
- Check Comcast/Cisco guidance for fixed firmware or replacement direction.
- Disable UI development mode wherever present.
- Restrict management/UI access to trusted administrative networks.
- Retire or replace affected legacy gateways if no supported fix exists.
Validation and detection
- Confirm whether any DPC3939 runs the named Comcast firmware build.
- Verify UI development mode is disabled in device configuration.
- Review firewall rules for remote access to the device UI.
- Check vendor advisories for updated mitigation or firmware status.
- Document unsupported devices for replacement planning.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
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CVE-2017-9485 mapping review
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Open ATT&CK lookup- Severity
- Unknown
- CVSS
- Not scored
- Known Exploited
- No
- Published
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CVSS and timeline data
No CVSS vectors or timeline events were available in the normalized CVE source material.
Source materials
- CVE List V5 sourceCVE List V5
- https://github.com/BastilleResearch/CableTap/blob/master/doc/advisories/bastille-28.session-cookie-write.txtCVE reference · x_refsource_MISC
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.