7.4

CVE-2026-20051: cisco cisco nx-os software Use of Uninitialized Variable

CVSS: 7.4v3.1HighDeferred
Published 25-02-2026Last modified 25-02-2026
Open JSON

Vulnerability summary

CVE-2026-20051 is a high (CVSS 7.4) Use of Uninitialized Variable vulnerability in cisco cisco nx-os software. EPSS estimates a 0.15% chance of exploitation in the next 30 days, higher than 4.2% of scored vulnerabilities.

Overall risk
30/100
0100
Medium · default modelHow is this calculated?
CVSS score
7.4/10
010
High · v3.1 (CVE.org)
EPSS score
0.15%
0%100%
Low · 0.00 pp in 30 days
KEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded

Timeline

  1. 25-02-2026
    PublishedVulnerability first disclosed.
  2. 25-02-2026
    Last modifiedVulnerability information updated.

Description

A vulnerability with the Ethernet VPN (EVPN) Layer 2 ingress packet processing of Cisco Nexus 3600 Platform Switches and Cisco Nexus 9500-R Series Switching Platforms could allow an unauthenticated, adjacent attacker to trigger a Layer 2 traffic loop. This vulnerability is due to a logic error when processing a crafted Layer 2 ingress frame. An attacker could exploit this vulnerability by sending a stream of crafted Ethernet frames through the targeted device. A successful exploit could allow the attacker to cause a Layer 2 Virtual eXtensible LAN (VxLAN) traffic loop, which, in turn, could result in a denial of service (DoS) condition. This Layer 2 loop could oversubscribe the bandwidth on network interfaces, which would result in all data plane traffic being dropped. To exploit this vulnerability, the attacker must be Layer 2-adjacent to the affected device. Note: To stop active exploitation of this vulnerability, manual intervention is required to both stop the crafted traffic and flap all involved network interfaces. For additional assistance if a Layer 2 loop that is related to this vulnerability is suspected, contact the Cisco Technical Assistance Center (TAC) or the proper support provider.

CVSS metrics

2 scores · 2 sources · 1 version

EPSS trend

Probability

0.15%

Chance of exploitation in the next 30 days

Percentile

4%

Versus all other CVEs

30-day change

0.00 pp

From 0.16% on 21-09-2026

21-09-202621-10-2026
EPSS score
0.15%

Known exploited

Compare KEV catalogs

Not in any of the 3 tracked catalogs.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Cisco1 product
  • cisco nx-os software9.2(3) | 9.2(2v) | 9.2(1) | 9.2(2t) | 9.2(3y) | 9.3(2) | 9.2(4) | 9.3(1) | 9.3(1z) | 9.2(2) | 9.3(3) | 9.3(4) | 9.3(5) | 9.3(6) | 9.3(5w) | 9.3(7) | 9.3(7k) | 10.2(1) | 9.3(7a) | 9.3(8) | 10.2(1q) | 10.2(2) | 9.3(9) | 10.2(3) | 10.2(3t) | 9.3(10) | 10.2(2a) | 10.3(1) | 10.2(4) | 10.3(2) | 9.3(11) | 10.3(3) | 10.2(5) | 9.3(12) | 10.2(3v) | 10.4(1) | 10.2(6) | 10.3(3w) | 10.3(3o) | 10.3(4) | 10.3(3p) | 10.3(4a) | 10.4(2) | 10.3(3q) | 9.3(13) | 10.3(5) | 10.2(7) | 10.4(3) | 10.3(3x) | 10.3(4g) | 10.5(1) | 10.2(8) | 10.3(3r) | 10.3(6) | 9.3(14) | 10.4(4) | 10.3(4h) | 10.5(2) | 10.3(7) | 10.4(5) | 10.5(3) | 10.2(9) | 9.3(15) | 10.4(4g) | 10.5(4) | 10.6(1) | 10.5(3t) | 10.3(8) | 10.4(6) | 10.5(3s) | 10.5(3e) | 10.5(3o) | 9.3(16) | 10.6(1s) | 10.5(3p)

1 vendor · 1 product

References

1 links