Security Advisory 0176

Date: September 9, 2026

Revision	Date	Changes
1.0	September 9, 2026	Initial release

The CVE-ID tracking this issue: CVE-2026-73469
CVSSv3.1 Base Score: 5.8 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N)
CVSSv4.0 Base Score: 6.9 (CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N)
Common Weakness Enumeration: CWE-863: Incorrect Authorization
This vulnerability is being tracked by BUG 1353206

Description

When specific platforms are using Arista EOS with a loose Unicast Reverse Path Forwarding (uRPF) configuration, certain traffic may not be subjected to the intended verification drop. Consequently, traffic that should be dropped based on these routes could still be processed and forwarded by the device.

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

Vulnerability Assessment

Affected Software

EOS Versions

4.35.4M and below releases in the 4.35.x train

Affected Platforms

The following products are affected by this vulnerability:

Arista EOS-based products:

7050X4 Series
7358X4 Series

The following product versions and platforms are not affected by this vulnerability:

Arista EOS-based products:

710 Series
720D Series
720XP/722XPM Series
750X Series
7010 Series
7010X Series
7020R Series
7130 Series running EOS
7150 Series
7160 Series
7170 Series
7050X/X2/X3 Series
7060X/X2/X4/X5/X6 Series
7250X Series
7260X/X3 Series
7280E/R/R2/R3/R4 Series
7300X/X3 Series
7320X Series
7368X4 Series
7388X5 Series
7500E/R/R2/R3 Series
7800R3/R4 Series
7700R4 Series
AWE 5000 Series
AWE 7200R Series
CloudEOS
cEOS-lab
vEOS-lab
CloudVision eXchange, virtual or physical appliance

Wi-Fi Access Points
CloudVision CUE, virtual appliance or physical appliance
CloudVision CUE cloud service delivery
CloudVision Portal, virtual appliance or physical appliance
CloudVision Appliance Software
CloudVision as-a-Service
CloudVision AGNI - Cloud service delivery
CloudVision AGNI - Virtual or physical appliance
Arista 7130 Systems running MOS
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-2026-73469, loose mode uRPF must be configured on an interface. This can be checked by showing the interface status, or by checking the current switch config.

switch>show ip interface
Ethernet1/1 is up, line protocol is up (connected)
  Internet address is 192.0.2.1/24
  Broadcast address is 255.255.255.255
  IPv4 interface forwarding: enabled
  IPv6 interface forwarding: none
  IP verify unicast source reachable-via any
  Proxy-ARP is disabled
  Local Proxy-ARP is disabled
  Gratuitous ARP is ignored
  ARP aging timeout is 14400 seconds
  IP MTU 1500 bytes
...
  
switch>show ipv6 interface
  
Ethernet1/1 is up, line protocol is up (connected)
  IPv6 is enabled, link-local is fe80::200:5eff:fe00:53fe/64
  Global unicast address(es):
    2001:db8::1, subnet is 2001:db8::/64
  Joined group address(es):
    ff02::1
    ff02::2
    ff02::1:ff00:1
    ff02::1:ff00:53fe
  IPv6 verify unicast source reachable-via any
  ND DAD is enabled, number of DAD attempts: 1
  ND Reachable time is 2147483000 milliseconds
  ND retransmit interval is 1000 milliseconds
  ND enhanced duplicate address detection enabled
  ND advertised reachable time is 2147483000 milliseconds (using 2147483000)
  ND advertised retransmit interval is 1000 milliseconds
  ND router advertisements are sent every 200 seconds
  ND router advertisements live for 1800 seconds
  ND advertised default router preference is Medium
  ND advertised maximum hop count limit is 64
  Hosts use stateless autoconfig for addresses.
  ND unsolicited NAs are not accepted
  ND cache expiry time is 14400 seconds
...
  
switch>show running-config section ip verify
interface Ethernet1/1
  ip verify unicast source reachable-via any
  
switch>show running-config section ipv6 verify
interface Ethernet1/1
  ipv6 verify unicast source reachable-via any

If loose mode uRPF is not configured on an interface, there is no exposure to this issue. In this example, Ethernet1/1 is configured with strict mode uRPF, and Ethernet2/1 is not configured with any uRPF. Therefore neither are affected.

switch>show ip interface
Ethernet1/1 is up, line protocol is up (connected)
  Internet address is 192.0.2.1/24
  Broadcast address is 255.255.255.255
  IPv4 interface forwarding: enabled
  IPv6 interface forwarding: none
  IP verify unicast source reachable-via RX
  Proxy-ARP is disabled
  Local Proxy-ARP is disabled
  Gratuitous ARP is ignored
  ARP aging timeout is 14400 seconds
  IP MTU 1500 bytes
Ethernet2/1 is up, line protocol is up (connected)
  Internet address is 198.51.100.1/24
  Broadcast address is 255.255.255.255
  IPv4 interface forwarding: enabled
  IPv6 interface forwarding: none
  Proxy-ARP is disabled
  Local Proxy-ARP is disabled
  Gratuitous ARP is ignored
  ARP aging timeout is 14400 seconds
  IP MTU 1500 bytes

Indicators of Compromise

No indicators of compromise exist.

Mitigation

No mitigation exists for this issue.

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-2026-73469 has been fixed in the following releases:

4.36.0F and later releases in the 4.36.x train
4.35.5M and later releases in the 4.35.x train

Hotfix

No hotfix is provided 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

Contact information needed to open a new service request may be found at:
https://www.arista.com/en/support/customer-support

Security Advisories