Security Advisory 0207 .CSAF PDF

Date: November 10, 2026

 

Revision Date Changes
1.0 November 10, 2026 Initial release

The CVE-ID tracking this issue: CVE-2026-120982
CVSSv3.1 Base Score: 7.5 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H)
CVSSv4.0 Base Score: 8.7 (CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N)
Common Weakness Enumeration: [CWE-440] Expected Behavior Violation
This vulnerability is being tracked by BUG 1927714

Description

On affected platforms running Arista EOS with Border Gateway Protocol (BGP) configured, An unauthenticated attacker who can establish a BGP peering session with an affected device and can send specially crafted BGP messages to cause repeated BGP session resets, enabling sustained disruption to network routing and traffic forwarding.

This issue was discovered internally by Arista, and the company is not aware of any malicious exploitation of this vulnerability in customer networks.

Vulnerability Assessment

Platform and Software Applicability Note

To determine actual exposure, operators should first check their software versions against the "Affected Software" list below. If your software release is not listed, your deployment is not vulnerable, regardless of the hardware platform in use.

Affected Software

EOS Versions

  • 4.36.2F and below releases in the 4.36.x train
  • 4.35.6M and below releases in the 4.35.x train
  • 4.34.8M and below releases in the 4.34.x train
  • 4.33.10M and below releases in the 4.33.x train
  • All releases in the End of Support software release trains

Affected Platforms

The following products are affected by this vulnerability:
 

 

  • Arista EOS-based products:
    • 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
 

 

The following product versions and platforms are not affected by this vulnerability:
 
  • Wi-Fi Access Points
  • CloudVision CUE cloud service delivery
  • CloudVision Portal on-premises, virtual appliance or physical appliance(including the CV-CUE on premises software)
  • CloudVision Appliance Software
  • CloudVision as-a-Service
  • CloudVision AGNI - Cloud service delivery
  • CloudVision AGNI - Virtual or physical appliance
  • Arista Converged Cloud Fabric (formerly Big Switch BCF)
  • DANZ Monitoring Fabric (DMF) - Controller Appliance
  • DANZ Monitoring Fabric (DMF) - Analytics Node Appliance
  • DANZ Monitoring Fabric (DMF) - Recorder Node Appliance
  • DANZ Monitoring Fabric (DMF) - Service Node Appliance
  • Arista Multi Cloud Director (formerly Big Switch MCD)
  • Arista Network Detection and Response (NDR) Security Platform (Formerly Awake NDR)
  • Arista Edge Threat Management - Arista NG Firewall and Arista Micro Edge (Formerly Untangle)
  • Arista NetVisor OS, Arista NetVisor UNUM, and Insight Analytics (Formerly Pluribus)
  • VeloCloud Orchestrator (Formerly VeloCloud Orchestrator by Broadcom)
  • VeloCloud Gateway (Formerly VeloCloud Gateway by Broadcom)
  • VeloCloud Edge (Formerly VeloCloud Edge by Broadcom)

Required Configuration for Exploitation

In order to be vulnerable to CVE-2026-120982, BGP must be configured AND the multi-agent routing protocol model must be in use on the device:

switch>show ip bgp summary
BGP router identifier X.X.X.X, local AS number XXXXX
...
Neighbor     V  AS      MsgRcvd   MsgSent  InQ OutQ  Up/Down State   PfxRcd PfxAcc
X.X.X.X      4  XXXXX   100       100      0   0     01:00:00 Estab  10     10
 
switch>show running-config all | inc service routing protocols
service routing protocols model multi-agent
 

 

If BGP is not configured OR if the multi-agent routing protocol model is not in use there is no exposure to this issue and the output will look like:

switch>show ip bgp summary
% BGP is not active
switch>show run all | inc service routing protocols
service routing protocols model ribd

Indicators of Compromise

A BGP session reset caused by this vulnerability will generate log messages indicating the session was terminated due to an UPDATE message error. The following messages may appear in `show logging`:

 

switch>show logging | grep "NOTIFICATION.*UPDATE Message Error"
 
BGP-3-NOTIFICATION: sent to neighbor X.X.X.X (VRF default) 3/5 (UPDATE Message Error/XXX Error) N bytes
%BGP-5-ADJCHANGE: peer X.X.X.X (VRF default) old state: Established event: SentNotification new state: Idle
 

Repeated occurrences of these log messages from the same or different peers may indicate exploitation of this vulnerability.

Mitigation

A workaround is to configure attribute discard:

 

router bgp <asn>
   neighbor default received attribute discard 22
 

 

The above configuration applies the mitigation globally. The attribute can be re-enabled on specific peers if it is required within the customer application. For example:

router bgp <asn>
   no neighbor X.X.X.X received attribute discard 22
 

The show bgp neighbors output can be used verify the configuration is applied correctly per peer:

switch> show bgp neighbors
…
  Configured received path attribute types to discard: 22
 

The “Configured received path attribute types to discard” will not be present or not contain the affected attribute if the configuration is not applied on a peer.

Note that enabling the attribute on any peer restores exposure to the issue.

Alternatively, a recommended mitigation to reduce exposure to this vulnerability is to configure BGP peer authentication using TCP-AO in order to ensure that only authorized peers can establish a BGP session.

Resolution

The recommended resolution is to upgrade to a remediated software version at your earliest convenience. Arista recommends customers move to the latest version of each release that contains all the fixes listed below. For more information about upgrading see EOS User Manual: Upgrades and Downgrades

CVE-2026-120982 has been fixed in the following releases:
 
  • 4.37.0F and later releases in the 4.37.x train
  • 4.36.3M and later releases in the 4.36.x train
  • 4.35.7M and later releases in the 4.35.x train
  • 4.34.9M and later releases in the 4.34.x train
  • 4.33.11M and later releases in the 4.33.x train

 

Hotfix

No hotfixes are available for this issue

For More Information

If you require further assistance, or if you have any further questions regarding this security notice, please contact the Arista Networks Technical Assistance Center (TAC) by one of the following methods:

  • Open a Service Request
  • By email: This email address is being protected from spambots. You need JavaScript enabled to view it.
  • By telephone: List of regional telephone numbers

Receive notification for new advisories and notices:

Subscribe to the RSS feed and email notifications to receive periodic updates on new software releases, advisories, end of sale and field notices.