CVE-2017-3803 Cisco CVE debrief

Who should care

Network and infrastructure teams running Cisco IOS on affected 2960X or 3750X switches, especially in environments where untrusted devices can share the same Layer 2 segment.

Technical summary

The vulnerability is described as a memory leak in the IOS software forwarding queue. NVD classifies the weakness as CWE-772 (Missing Release of Resource after Effective Lifetime). The supplied record lists affected releases 15.2(2)E3 and 15.2(4)E1, with fixed releases including 15.2(2)E6, 15.2(4)E3, 15.2(5)E1, 15.2(5.3.28i)E1, 15.2(6.0.49i)E, and 3.9(1)E. The CVSS vector is CVSS:3.0/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:L.

Defensive priority

Medium. The issue is unauthenticated and can be triggered by an adjacent attacker, but the impact is limited to availability and described as partial DoS rather than full device compromise.

Recommended defensive actions

• Inventory Cisco 2960X and 3750X switches and confirm the running IOS release.
• Upgrade any affected devices to a fixed release listed in the supplied record.
• Prioritize remediation on switches exposed to untrusted adjacent networks or shared Layer 2 segments.
• Monitor for abnormal resource growth or instability on affected switches until patched.
• Review Cisco's advisory and vendor guidance before scheduling maintenance windows.

Evidence notes

This debrief is based on the supplied NVD record for CVE-2017-3803 and the Cisco advisory references embedded in that record. The key facts used are: unauthenticated adjacent attack conditions, memory leak in the software forwarding queue, partial DoS impact, affected and fixed releases, and the NVD-assigned CWE-772 classification. No advisory body text was supplied, so mitigation details are limited to version-based upgrading and the referenced vendor documentation.

Official resources