CVE-2026-121370 PUBLISHED

Security Advisory 0224

Assigner: Arista
Reserved: 03.11.2026 Published: 10.11.2026 Updated: 10.11.2026

On affected platforms running Arista EOS with Precision Time Protocol (PTP) configured, an unauthenticated attacker with network access to a PTP-enabled port can create a denial of service (DoS) condition by sending traffic to the system.

CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
CVSS Score: 8.6

Attack Vector	Network	Scope	Changed
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:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:H
CVSS Score: 9.2

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	None	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 4.34.0F to 4.34.1F (incl.) affected from 4.33.0F to 4.33.8M (incl.) affected from 4.32.0F to 4.33.0F (excl.) affected from 4.31.0F to 4.32.0F (excl.) affected from 4.30.0F to 4.31.0F (excl.) affected from 4.29.2F to 4.30.0F (excl.)

Affected Configurations

switch>show ptp PTP Mode: Boundary Clock PTP Profile: Default ( IEEE1588 ) Clock Identity: XX:XX:XX:XX:XX:XX:XX:XX Grandmaster Clock Identity: XX:XX:XX:XX:XX:XX:XX:XX Number of slave ports: 0 Number of master ports: 1 Offset From Master (nanoseconds): 0 Mean Path Delay (nanoseconds): 0 Steps Removed: 0 Skew (estimated local-to-master clock frequency ratio): 1.0 Interface State Transport Delay<br /> Mechanism

<hr />

Et1 Master ipv4 e2e

Workarounds

switch# platform trident Linecard diag mod MMU_MAX_BUCKET_QLAYER 1 1 THD_SEL=0x4d REFRESH=0x28 switch# platform trident Linecard diag mod MMU_MIN_BUCKET_QLAYER 1 1 THD_SEL=0x10 REFRESH=0x8

Note: If PTP is currently enabled on any interfaces, disable it on those interfaces before running the mitigation commands, then re-enable it afterward.

To disable PTP on an interface: switch(config-if)# no ptp enable

Note: These settings are not persistent. They must be re-applied after any forwarding plane reset or line card replacement.

References

https://www.arista.com/en/support/advisories-notices/security-advisory/25046-security-advisory-0224

Problem Types

CWE-770 Allocation of Resources Without Limits or Throttling CWE

Impacts

CAPEC-130 Excessive Allocation