CVE-2026-20038: Improper Access Control in Cisco Cisco NX-OS System Software in ACI Mode
Description
A vulnerability in the endpoint group (EPG) contract functionality of Cisco Nexus 9000 Series Fabric Switches in ACI Mode could allow an unauthenticated, remote attacker to bypass configured EPG contracts. This vulnerability is due to an improper control with EPG contracts. An attacker could exploit this vulnerability by sending IPv4 or IPv6 packets using UDP source and destination ports that are assigned to DHCP traffic through an affected device. A successful exploit could allow the attacker to bypass EPG contracts on the affected device.
CVSS v3.1
Score 5.8medium
Affected software
Cisco
Cisco NX-OS System Software in ACI Mode
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
This vulnerability affects the EPG contract functionality of Cisco Nexus 9000 Series Fabric Switches in ACI Mode. Due to improper control of EPG contracts, an attacker can send IPv4 or IPv6 UDP packets with source and destination ports assigned to DHCP traffic to bypass the configured EPG contracts on the affected device. The vulnerability does not require authentication and has a CVSS 3.1 base score of 5.8, indicating medium severity. No known exploits in the wild or vendor patch information is provided in the available data.
Potential Impact
Successful exploitation allows an unauthenticated remote attacker to bypass EPG contracts, potentially enabling unauthorized network traffic to traverse the fabric switch contrary to configured policies. This could lead to limited integrity impact but no confidentiality or availability impact as per the CVSS vector.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. No official fix or workaround information is provided in the available data. Until a patch is available, monitoring and restricting DHCP traffic where possible may reduce risk.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- cisco
- Date Reserved
- 2025-10-08T11:59:15.354Z
- Cvss Version
- 3.1
- State
- PUBLISHED
Threat ID: 6ac674862cdf04f65664731b
Added to database: 10/07/2026, 16:34:14 UTC
Last enriched: 10/07/2026, 17:04:49 UTC
Last updated: 10/08/2026, 05:48:07 UTC
Views: 11
Community Reviews
0 reviewsCrowdsource mitigation strategies, share intel context, and vote on the most helpful responses. Sign in to add your voice and help keep defenders ahead.
Want to contribute mitigation steps or threat intel context? Sign in or create an account to join the community discussion.
Actions
Updates to AI analysis require Pro Console access. Upgrade inside Console → Billing.
External Links
Need more coverage?
Upgrade to Pro Console for AI refresh and higher limits.
For incident response and remediation, OffSeq services can help resolve threats faster.
Latest Threats
Check if your credentials are on the dark web
Instant breach scanning across billions of leaked records. Free tier available.