CVE-2026-73436

Security Advisory 0171

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

On affected platforms running Arista EOS with OSPFv2 and OSPFv2 segment routing configured, a specially crafted OSPFv2 packet from an adjacent OSPF neighbor may cause OSPF to restart unexpectedly.

Metrics

CVSS Vector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CVSS Score: 6.5

Attack Vector	Adjacent 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:A/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
CVSS Score: 6

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

CVSS 4.0

Product Status

Vendor	Arista Networks
Product	EOS
Versions	Default: unaffected affected from 4.36.0F to 4.36.1F (incl.) affected from 4.35.0F to 4.35.5M (incl.) affected from 4.34.0F to 4.34.7.1M (incl.) affected from 4.33.0F to 4.33.9M (incl.) affected from 1.0.0 to 4.33.0F (excl.)

Vendor

Arista Networks

Product

EOS

Versions

Default: unaffected

affected from 4.36.0F to 4.36.1F (incl.)
affected from 4.35.0F to 4.35.5M (incl.)
affected from 4.34.0F to 4.34.7.1M (incl.)
affected from 4.33.0F to 4.33.9M (incl.)
affected from 1.0.0 to 4.33.0F (excl.)

Affected Configurations

In order to be vulnerable to CVE-2026-73436, the following condition must be met:

OSPFv2 segment routing must be configured. If the below command shows any OSPF instance, then the deployment is vulnerable.

switch>show ip ospf segment-routing SPF Instance ID: 1 ...

If OSPFv2 segment routing is not configured, then there is no exposure to this issue.

Workarounds

No mitigation is available for CVE-2026-73436.

Solutions

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.

CVE-2026-73436 has been fixed in the following releases: - 4.36.2F and later releases in the 4.36.x train - 4.35.6M and later releases in the 4.35.x train - 4.34.8M and later releases in the 4.34.x train - 4.33.10M and later releases in the 4.33.x train

No hotfix is available for CVE-2026-73436.

References

Problem Types

CWE-1284 Improper Validation of Specified Quantity in Input CWE
CWE-125 Out-of-bounds Read CWE

CVE-2026-73436 PUBLISHED