CVE-2026-20038

Read full 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 5.8 (MEDIUM)

Attention and evidence

HYPE SCORE

1.4/10

REALITY · THREAT PRIORITY

2.0/10

General review priority; not probability

Evidence confidence: Insufficient evidence

Why this priority?

Technical severity: CVSS 5.8: +2.03
Fresh EPSS: 0.30%: +0.01

General review priority, not probability, victim count or asset-specific risk. A range covers missing CVSS/EPSS inputs within the current evidence state.

Sources: 4 documents and public datasets.

Hype components

Headline sample (25%)

30/100

Press, 30 days (60%)

10/100

Grounded branding (15%)

0/100

HYPE TOTAL14/100

Sources and documents

Cisco Security Advisory

Technical advisory · 07 Oct 2026, 16:00 · Cisco Advance Notification for Publication of October 7, 2026, Security Advisories

Cisco Security Advisory

Press · 07 Oct 2026, 16:00 · Cisco Advance Notification for Publication of October 7, 2026, Security Advisories

Cisco Security Advisory

Technical advisory · 07 Oct 2026, 16:00 · Cisco Nexus 9000 Series Fabric Switches in ACI Mode Endpoint Group Contract Bypass Vulnerability

Cisco Security Advisory

Press · 07 Oct 2026, 16:00 · Cisco Nexus 9000 Series Fabric Switches in ACI Mode Endpoint Group Contract Bypass Vulnerability

Score evolution

● Hype ● Reality

Earlier evidence-support scores are retained in history; this chart shows only the current priority definition.

First record: hype 1.4 · reality 2.0 (2026-11-02 15:14). The curve appears once the score changes.

Public exploit evidence

Public exploit entries / repo candidates

Evidence context and dated references

Reality is general threat/review priority, combining observed exploitation, CVSS severity and fresh EPSS. Evidence confidence is separate. This is not calibrated risk, a victim count or an asset-specific assessment. A range reflects missing numeric inputs. Published 29 days ago. Exploitation evidence usually takes weeks to show up: a low reality score can mean there is no data yet, not that the flaw is mild.

Evidence in context

Confidence in exploitation evidence: Insufficient evidence
Priority basis: Exploitation in attacks unconfirmed; CVSS 5.8; EPSS 0.3%
Attention, last 30 days: 2 distinct story titles; 2 press documents; 1 publisher domains.
Technical potential: network access, no prior privileges, no user interaction.
Observed activity: No exploitation observation is recorded.
Known scale: Not quantified.
Evidence confidence basis: Insufficient evidence

Score evaluated: 2026-11-05 14:00:00.097835+00:00 · EPSS snapshot: 2026-11-05T12:03:04Z

Source event timeline

First press mention

07 Oct 2026, 16:00

Latest press mention

07 Oct 2026, 16:00

Published

07 Oct 2026, 16:11

Score calculated

05 Nov 2026, 14:00