An unauthenticated P4Runtime (Programming Protocol-Independent Packet Processors Runtime) client can achieve arbitrary code execution under certain conditions on affected platforms running Arista EOS configured with P4Runtime. P4Runtime is disabled by default in Arista EOS. By crafting a malicious packet during the initiation of a P4Runtime session, an attacker can obtain complete administrative control over the compromised switch.
This issue was discovered internally by Arista, and the company is not aware of any malicious exploitation of this vulnerability in customer networks.
In order to be vulnerable to CVE-2026-73453, p4-runtime must be configured in one of the following combinations. P4-runtime is not a feature which runs by default and must be explicitly enabled:
- Non TLS mode (p4-runtime is enabled with no ssl profile configured):
switch>show p4-runtime
Enabled: yes
Server: running on port 9559, in mgmtVrf VRF
SSL profile: none
Authentication username priority: x509-spiffe, x509-common-name
Total clients: 0
Accounting requests: no
- TLS mode (p4-runtime is enabled and ssl profile is configured with no trusted certificates):
switch>show p4-runtime
Enabled: yes
Server: running on port 9559, in mgmtVrf VRF
SSL profile: campus
Authentication username priority: x509-spiffe, x509-common-name
Total clients: 0
Accounting requests: no
switch>show management security ssl profile campus detail
Profile: campus
State: valid
Trusted certificates: n/a
- mTLS mode (p4-runtime is enabled and ssl profile is configured with trusted certificates) + Accounting is enabled for p4-runtime service OR gNSI acctz is enabled + gNSI Authz is disabled:
switch>show p4-runtime
Enabled: yes
Server: running on port 9559, in mgmtVrf VRF
SSL profile: campus
Authentication username priority: x509-spiffe, x509-common-name
Total clients: 0
Accounting requests: yes
switch>show management security ssl profile campus detail
Profile: campus
State: valid
Trusted certificates:
- clientRootCa
switch>show management api gnsi
Transport: no transport configured
Acctz enabled: yes
Attestz enabled: no
Authz enabled: no
Certz enabled: no
Credentialz enabled: no
Enrollz enabled: no
Pathz enabled: no
If P4Runtime is not configured there is no exposure to this issue:
switch>show p4-runtime
Enabled: no
To mitigate this issue, it is recommended to configure the p4-runtime service in mTLS mode (ssl profile with trust certificates). Additionally, enable gNSI Authz to facilitate RPC authorization via the client certificate SPIFFE-ID. Please note that enabling mTLS config will terminate all existing P4 client connections and may cause control plane disruption since packet I/O operations are impacted.
Before implementing this solution, the following pre-requisites must be met:
- Generate SPIFFE-ID client certificate signed by the server trusted CA and use it for establishing P4 client connection to the server.
- Define a json file with SPIFFE-ID based policies for Authz service and install it on the device using gNSI Authz.Rotate() rpc.
switch>show running-config section p4-runtime
p4-runtime
no shutdown
!
transport grpc foo
ssl profile campus
authentication username priority x509-spiffe
switch>show running-config section security
management security
ssl profile campus
certificate server.crt key server.key
trust certificate ca.crt
switch>show running-config section gnsi
management api gnsi
service authz
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-2026-73453 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
No hotfix is available for this issue.