EOS: Insufficient Verification of Data Authenticity
CVE-2026-73435 is a high-severity insufficient verification of data authenticity vulnerability in EOS from Arista Networks, with a CVSS 3.1 base score of 8.2 out of 10. It can be exploited from the same local network by an unauthenticated attacker, without any action from a user. The record lists version 4.33.0F as the first without the flaw, so updating EOS to that release or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.19% chance of exploitation within 30 days, which is low compared with other CVEs.
High severity with no evidence of exploitation so far.
What to do
- Update EOS to 4.33.0F or a later version.
- Read the advisory on arista.com for workarounds and exact fixed builds.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Arista Networks | EOS | 4.36.0F through 4.36.1F; 4.35.0F through 4.35.5M; 4.34.0F through 4.34.7M; 4.33.0F through 4.33.9M; 1.0.0 up to, but not including, 4.33.0F | 4.33.0F |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- AdjacentThe attacker must be on the same local network segment.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- NoneNo action by a victim is required.
- Scope
- ChangedThe attack can reach beyond the vulnerable component into other systems.
- Confidentiality
- NoneNo data is disclosed.
- Integrity
- LowLimited modification of data is possible.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:H. Scored by CNA (arista.com).
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 4.0 | 7.0 | High | CNA (arista.com) |
| CVSS 3.1 | 8.2 | High | CNA (arista.com) |
Official description
On affected platforms running Arista EOS with Open Shortest Path First version 2 (OSPFv2) configured, a specially crafted OSPFv2 packet from an unauthenticated attacker on the same broadcast segment, with OSPFv2 authentication configured can cause adjacency flapping and packet loss. The disruption can affect routing across the broader OSPF domain.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Insufficient Verification of Data Authenticity
The product does not sufficiently verify the origin or authenticity of data, in a way that causes it to accept invalid data.
More Insufficient Verification of Data Authenticity vulnerabilities (CWE-345)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: partial).
References
Other vulnerabilities in EOS
- 7.5 High severity
- 8.6 High severity
- 8.6 High severity
- 9.6 Critical severity
- 8.6 High severity
- 8.2 High severity
Recent Insufficient Verification of Data Authenticity vulnerabilities
- 8.1 High severity
- 8.2 High severity
- 8.6 High severity
- 9.6 Critical severity
- 8.2 High severity
- 8.6 High severity
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