CVE-2026-73455 PUBLISHED

Security Advisory 0173

Assigner: Arista
Reserved: 12.08.2026 Published: 16.09.2026 Updated: 16.09.2026

On affected platforms running Arista EOS with Open Shortest Path First version 3 (OSPFv3) configured, a specially crafted packet can cause the OSPFv3 agent to restart unexpectedly.

CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CVSS Score: 7.5

Attack Vector	Network	Scope	Unchanged
Attack Complexity	Low	Confidentiality Impact	None
Privileges Required	None	Integrity Impact	None
User Interaction	None	Availability Impact	High

CVSS 3.1

CVSS Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:H
CVSS Score: 8.9

Exploitability Metrics		Vulnerable System Impact Metrics		Subsequent System Impact Metrics
Attack Vector	Network	Confidentiality	None	Confidentiality	None
Attack Complexity	Low	Integrity	None	Integrity	None
Attack Requirements	Present	Availability	High	Availability	High
Privileges Required	None
User Interaction	None

CVSS 4.0

Product Status

Vendor	Arista Networks
Product	EOS
Versions	Default: unaffected affected from 1.0.0 to 4.33.0F (excl.) affected from 4.33.0F to 4.33.8M (incl.) affected from 4.34.0F to 4.34.6M (incl.) affected from 4.35.0F to 4.35.4M (incl.) affected from 4.36.0F to 4.36.0.1F (incl.)

Affected Configurations

The vulnerability is exploitable when OSPFv3 is configured with at least one active neighbor:

switch>show ospfv3 Routing Process "ospfv3" with ID 192.0.2.0 and Instance 0 VRF default It has 1 fully adjacent neighbors

switch>show ospfv3 neighbor Neighbor 192.0.3.0 VRF default priority is 1, state is Full

Workarounds

Configure OSPFv3 IPsec encryption to authenticate/encrypt OSPFv3 packets.

Per-interface encryption:

switch(config)# interface <interface-name> switch(config-if)# ospfv3 encryption ipsec spi <spi-value> esp aes-256-cbc sha1 passphrase <shared-passphrase>

Per-area encryption:

switch(config)# router ospfv3 switch(config-router-ospfv3)# address-family ipv4 switch(config-router-ospfv3-af)# area <area-id> encryption ipsec spi <spi-value> esp aes-256-cbc sha1 passphrase <shared-passphrase>

Solutions

The following EOS releases contain the fix: - 4.33.9M and later in the 4.33.x train - 4.34.7M and later in the 4.34.x train - 4.35.5M and later in the 4.35.x train - 4.36.1F and later in the 4.36.x train

A hotfix (version 1.0) is available for 4.36.0.1F, 4.35.4M, 4.34.6M, and 4.33.8M.

References

https://www.arista.com/en/support/advisories-notices/security-advisory/24729-security-advisory-0173

Problem Types

CWE-130 Improper Handling of Length Parameter Inconsistency CWE

Impacts

CAPEC-231 Oversized Serialized Data Payloads