Security Advisory 0209

Summary

CVE	CVE-2026-121290
State	PUBLISHED
Assigner	Arista
Source Priority	CVE Program / NVD first with legacy fallback
Published	2026-11-10 20:18:54 UTC
Updated	2026-11-10 20:18:54 UTC
Description	On affected platforms running Arista EOS with Border Gateway Protocol (BGP) changing the BGP listen port from its default value disables default protective Access Control List (ACL) rules against unexpected BGP peering attempts.

Risk And Classification

Primary CVSS: v4.0 8.3 HIGH from [email protected]

CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Problem Types: CWE-420 | CWE-420 CWE-420 Unprotected Alternate Channel

Version	Source	Type	Score	Severity	Vector
4.0	[email protected]	Secondary	8.3	HIGH	`CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:H/SC:N/SI:N/SA:N/E:X/C...`
4.0	CNA	DECLARED	8.3	HIGH	`CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:H/SC:N/SI:N/SA:N`
3.1	[email protected]	Secondary	8.2	HIGH	`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H`
3.1	CNA	DECLARED	8.2	HIGH	`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H`

CVSS v4.0 Breakdown

Attack Vector

Network

Attack Complexity

Low

Attack Requirements

Present

Privileges Required

None

User Interaction

None

Confidentiality

None

Integrity

Low

Availability

High

Sub Conf.

None

Sub Integrity

None

Sub Availability

None

CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

CVSS v3.1 Breakdown

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

Low

Availability

High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H

Vendor Declared Affected Products

Source	Vendor	Product	Version	Platforms
CNA	Arista Networks	EOS	affected 4.36.0F 4.36.2F custom	710 Series, 720D Series, 720XP/722XPM Series, 750X Series, 7010TX Series, 7020R/R4 Series, 7130 Series running EOS, 7170 Series, 7050X3/X4 Series, 7060X/X2/X4/X5/X6/XE7 Series, 7260X/X3 Series, 7280R/R2/R3/R4 Series, 7300X/X3 Series, 7320X Series, 7358X4 Series, 7368X4 Series, 7388X5 Series, 7500R/R2/R3 Series, 7800R3/R4 Series, 7700R4 Series, AWE 5000 Series, AWE 7200R Series, ZTX-7200 Series, CloudEOS, cEOS-lab, vEOS-lab, CloudVision eXchange, virtual or physical appliance
CNA	Arista Networks	EOS	affected 4.35.0F 4.35.6M custom	710 Series, 720D Series, 720XP/722XPM Series, 750X Series, 7010TX Series, 7020R/R4 Series, 7130 Series running EOS, 7170 Series, 7050X3/X4 Series, 7060X/X2/X4/X5/X6/XE7 Series, 7260X/X3 Series, 7280R/R2/R3/R4 Series, 7300X/X3 Series, 7320X Series, 7358X4 Series, 7368X4 Series, 7388X5 Series, 7500R/R2/R3 Series, 7800R3/R4 Series, 7700R4 Series, AWE 5000 Series, AWE 7200R Series, ZTX-7200 Series, CloudEOS, cEOS-lab, vEOS-lab, CloudVision eXchange, virtual or physical appliance
CNA	Arista Networks	EOS	affected 4.34.0F 4.34.8M custom	710 Series, 720D Series, 720XP/722XPM Series, 750X Series, 7010TX Series, 7020R/R4 Series, 7130 Series running EOS, 7170 Series, 7050X3/X4 Series, 7060X/X2/X4/X5/X6/XE7 Series, 7260X/X3 Series, 7280R/R2/R3/R4 Series, 7300X/X3 Series, 7320X Series, 7358X4 Series, 7368X4 Series, 7388X5 Series, 7500R/R2/R3 Series, 7800R3/R4 Series, 7700R4 Series, AWE 5000 Series, AWE 7200R Series, ZTX-7200 Series, CloudEOS, cEOS-lab, vEOS-lab, CloudVision eXchange, virtual or physical appliance
CNA	Arista Networks	EOS	affected 4.33.0F 4.33.10M custom	710 Series, 720D Series, 720XP/722XPM Series, 750X Series, 7010TX Series, 7020R/R4 Series, 7130 Series running EOS, 7170 Series, 7050X3/X4 Series, 7060X/X2/X4/X5/X6/XE7 Series, 7260X/X3 Series, 7280R/R2/R3/R4 Series, 7300X/X3 Series, 7320X Series, 7358X4 Series, 7368X4 Series, 7388X5 Series, 7500R/R2/R3 Series, 7800R3/R4 Series, 7700R4 Series, AWE 5000 Series, AWE 7200R Series, ZTX-7200 Series, CloudEOS, cEOS-lab, vEOS-lab, CloudVision eXchange, virtual or physical appliance
CNA	Arista Networks	EOS	affected 4.32.0F 4.33.0F custom	710 Series, 720D Series, 720XP/722XPM Series, 750X Series, 7010TX Series, 7020R/R4 Series, 7130 Series running EOS, 7170 Series, 7050X3/X4 Series, 7060X/X2/X4/X5/X6/XE7 Series, 7260X/X3 Series, 7280R/R2/R3/R4 Series, 7300X/X3 Series, 7320X Series, 7358X4 Series, 7368X4 Series, 7388X5 Series, 7500R/R2/R3 Series, 7800R3/R4 Series, 7700R4 Series, AWE 5000 Series, AWE 7200R Series, ZTX-7200 Series, CloudEOS, cEOS-lab, vEOS-lab, CloudVision eXchange, virtual or physical appliance
CNA	Arista Networks	EOS	affected 1.0.0 4.32.0F custom	710 Series, 720D Series, 720XP/722XPM Series, 750X Series, 7010TX Series, 7020R/R4 Series, 7130 Series running EOS, 7170 Series, 7050X3/X4 Series, 7060X/X2/X4/X5/X6/XE7 Series, 7260X/X3 Series, 7280R/R2/R3/R4 Series, 7300X/X3 Series, 7320X Series, 7358X4 Series, 7368X4 Series, 7388X5 Series, 7500R/R2/R3 Series, 7800R3/R4 Series, 7700R4 Series, AWE 5000 Series, AWE 7200R Series, ZTX-7200 Series, CloudEOS, cEOS-lab, vEOS-lab, CloudVision eXchange, virtual or physical appliance

References

Reference	Source	Link	Tags
www.arista.com/en/support/advisories-notices/security-advisory/25031-securit...	[email protected]	www.arista.com
CVE Program record	CVE.ORG	www.cve.org	canonical
NVD vulnerability detail	NVD	nvd.nist.gov	canonical, analysis

No vendor comments have been submitted for this CVE.

Additional Advisory Data

Workarounds

CNA: router bgp <asn> no bgp transport listen-port If the non-default listen port must be retained, the required modifications to the control plane ACL (to allow the non-default listen port to be reached) should be made in such a manner to provide the desired protection — only allowing TCP connections using the non-default listen port when the remote IP address is an expected one, and if applicable, when the TTL value is within the expected range.

There are currently no legacy QID mappings associated with this CVE.