CVE-2017-3826 Cisco CVE debrief

Who should care

Organizations operating Cisco NGA 3140, 3240, or 3340 appliances, especially where NGA data ports monitor networks that may carry SCTP traffic. Security and infrastructure teams responsible for traffic monitoring, appliance uptime, and maintenance windows should prioritize review.

Technical summary

Cisco describes the flaw as incomplete validation of SCTP packets in the NGA decoder. Malformed SCTP packets on a network monitored by an NGA data port may cause the appliance to become unresponsive or reload, resulting in DoS. Cisco notes that SCTP packets addressed to the NGA device IP itself do not trigger the issue. The vulnerable software versions listed in NVD include 1.0(2), 1.0.0, 1.1(1), and 1.1.0, with remediation in 1.1(1a) or later. NVD rates the issue CVSS 3.0 7.5 HIGH (AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H).

Defensive priority

High. The flaw is network-reachable, unauthenticated, and can disrupt appliance availability. Systems using affected NGA software should be reviewed and upgraded promptly, especially if the appliance sits on networks that can carry SCTP traffic.

Recommended defensive actions

• Upgrade Cisco NetFlow Generation Appliance software to 1.1(1a) or later, per Cisco's advisory.
• Inventory NGA 3140, 3240, and 3340 appliances and confirm the installed software version against the vulnerable versions listed by NVD and Cisco.
• Review whether monitored networks carry SCTP traffic; if SCTP is not required, consider filtering or restricting it at upstream controls.
• Monitor affected appliances for unexpected hangs, reloads, or loss of service, and validate recovery procedures before maintenance windows.
• Ensure operators know the vendor-recommended recovery path if the appliance becomes unresponsive after traffic-triggered failure.
• Use the Cisco advisory as the primary remediation reference and verify exposure in your environment rather than relying only on generic CPE matching.

Evidence notes

Cisco's advisory and the NVD record both describe an unauthenticated remote DoS caused by incomplete SCTP packet validation on NGA data ports. The CVSS vector in NVD is CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H. NVD also lists CWE-20 as the primary weakness and CWE-399 as a secondary weakness. The CVE was published on 2017-03-01 and the NVD record was last modified on 2026-05-13. Note: NVD's hardware CPE entries for NGA models are marked vulnerable:false, so the Cisco advisory description is the best source for affected appliance context.

Official resources