On affected platforms running Arista EOS with VRRPv2 IP-AH authentication configured, an unauthenticated attacker within the same layer 2 network segment on which VRRP is running can capture a legitimate authenticated VRRP advertisement and replay it indef
Published Sep 16, 2026
5.3
MEDIUMCVSS 4.0
EPSS 0.27%
Description
On affected platforms running Arista EOS with VRRPv2 IP-AH authentication configured, an unauthenticated attacker within the same layer 2 network segment on which VRRP is running can capture a legitimate authenticated VRRP advertisement and replay it indefinitely. Replayed advertisements can be used to advertise stale VRRP state, for example to prevent a backup router from taking over the virtual gateway after the original master has gone down, resulting in a denial of service for hosts using the virtual gateway address.
Affected products
-
- Version 4.33.0StatusaffectedConstraints<=4.33.9M
- Version 4.34.0StatusaffectedConstraints<=4.34.7M
- Version 4.35.0StatusaffectedConstraints<=4.35.5M
- Version 4.36.0StatusaffectedConstraints<=4.36.1F
- Version
Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).
| Vendor | Product | Default status | Versions | |||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Arista Networks | EOS | unaffected |
|
No data.
No data.
No Red Hat product state for this CVE.
No package ranges for this CVE.
Remediation
Vendor solution
The recommended resolution is to upgrade to a remediated software version at your earliest convenience.
Important: Upgrading alone is not sufficient. The replay protection introduced by the fix is disabled by default and must be explicitly enabled with the following new global configuration command after upgrading to a remediated release:
switch(config)#vrrp ipv4 authentication anti-replay
CVE-2026-73443 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
Metrics
CVSS:4.0/AV:A/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N
1 other source (NVD) ▾
CVSS:4.0/AV:A/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/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:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:L
No CVSS v3.0 score for this CVE.
No CVSS v2.0 score for this CVE.
This CVE is not in the KEV list.
CISA SSVC (Vulnrichment)
Stakeholder-Specific Vulnerability Categorization from CISA ADP.
Exploitation
NoneAutomatable
NoTechnical Impact
PartialDecision
n/aAssessed Sep 17, 2026 · SSVC 2.0.3
Estimated probability of exploitation in the wild in the next 30 days (FIRST EPSS). As of Oct 1, 2026.
Score over time
Sep–Oct 2026- EPSS v5
Percentile over time
- EPSS v5
Table of values (2 key points)
Flat stretches are collapsed; showing up to 120 newest points.
| Date | Score | Percentile | Model |
|---|---|---|---|
| Oct 1, 2026 | 0.27% (0.00273) | 17.82th | v5 (v2026.06.15) |
| Sep 17, 2026 | 0.27% (0.00273) | 19.82th | v5 (v2026.06.15) |
References (1)
- https://www.arista.com/en/support/advisories-notices/security-advisory/24713-security-advisory-0157 vendor-advisory
| Link | Providers | Tags |
|---|---|---|
| https://www.arista.com/en/support/advisories-notices/security-advisory/24713-security-advisory-0157 | vendor-advisory |
Change history (0)
No recorded changes yet.