CVE-2026-20051 (GCVE-0-2026-20051)
Vulnerability from cvelistv5 – Published: 2026-02-25 16:14 – Updated: 2026-02-25 19:05
VLAI?
Title
Cisco Nexus 3600-R and 9500-R Series Switching Platforms Layer 2 Loop Denial of Service Vulnerability
Summary
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.
Severity ?
7.4 (High)
CWE
- CWE-457 - Use of Uninitialized Variable
Assigner
References
Impacted products
| Vendor | Product | Version | ||
|---|---|---|---|---|
| Cisco | Cisco NX-OS Software |
Affected:
9.2(3)
Affected: 9.2(2v) Affected: 9.2(1) Affected: 9.2(2t) Affected: 9.2(3y) Affected: 9.3(2) Affected: 9.2(4) Affected: 9.3(1) Affected: 9.3(1z) Affected: 9.2(2) Affected: 9.3(3) Affected: 9.3(4) Affected: 9.3(5) Affected: 9.3(6) Affected: 9.3(5w) Affected: 9.3(7) Affected: 9.3(7k) Affected: 10.2(1) Affected: 9.3(7a) Affected: 9.3(8) Affected: 10.2(1q) Affected: 10.2(2) Affected: 9.3(9) Affected: 10.2(3) Affected: 10.2(3t) Affected: 9.3(10) Affected: 10.2(2a) Affected: 10.3(1) Affected: 10.2(4) Affected: 10.3(2) Affected: 9.3(11) Affected: 10.3(3) Affected: 10.2(5) Affected: 9.3(12) Affected: 10.2(3v) Affected: 10.4(1) Affected: 10.2(6) Affected: 10.3(3w) Affected: 10.3(3o) Affected: 10.3(4) Affected: 10.3(3p) Affected: 10.3(4a) Affected: 10.4(2) Affected: 10.3(3q) Affected: 9.3(13) Affected: 10.3(5) Affected: 10.2(7) Affected: 10.4(3) Affected: 10.3(3x) Affected: 10.3(4g) Affected: 10.5(1) Affected: 10.2(8) Affected: 10.3(3r) Affected: 10.3(6) Affected: 9.3(14) Affected: 10.4(4) Affected: 10.3(4h) Affected: 10.5(2) Affected: 10.3(7) Affected: 10.4(5) Affected: 10.5(3) Affected: 10.2(9) Affected: 9.3(15) Affected: 10.4(4g) Affected: 10.5(4) Affected: 10.6(1) Affected: 10.5(3t) Affected: 10.3(8) Affected: 10.4(6) Affected: 10.5(3s) Affected: 10.5(3e) Affected: 10.5(3o) Affected: 9.3(16) Affected: 10.6(1s) Affected: 10.5(3p) |
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Sightings
| Author | Source | Type | Date |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
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