What is CVE-2026-20038?
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.
The record classifies CVE-2026-20038 under weakness class CWE-284. Its CVSS v3 base vector states that the flaw is reachable remotely over the network, needs no prior authentication, needs no user interaction. 1 affected-product entry is recorded, across 1 vendor, listed below. The identifier was first published 3 days ago.
Severity and exploitation probability
- CVSS v3.1 base score
- 5.8 — MEDIUM
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N - EPSS (FIRST)
- 0.3% probability of exploitation in the next 30 days, higher than 20.9% of all scored CVEs
- CISA KEV
- Not listed in the CISA Known Exploited Vulnerabilities catalog
- Threadlinqs priority
- 3.7/10 — a Threadlinqs composite of the CVSS base score, the EPSS percentile and public exploit availability
- Published
- 2026-10-07
Is CVE-2026-20038 being exploited?
It currently carries a trending score of 39 in the Threadlinqs vulnerability feed.
Affected products and versions
- Cisco: NX-OS System Software in ACI Mode
How to fix CVE-2026-20038
No vendor patch reference has been recorded for CVE-2026-20038 in the tracked sources. Follow the references below for a fix, and treat the products listed above as exposed until the vendor states otherwise.
Threat activity tracking CVE-2026-20038
1 tracked threat in the Threadlinqs corpus references CVE-2026-20038, either in the campaign’s CVE list or as an indicator on the campaign record.
Sources
Enriched from CVE.org, FIRST EPSS. Last verified by Threadlinqs on .