EOS: Improper Validation of Integrity Check Value
CVE-2026-73459 is a high-severity improper validation of integrity check value vulnerability in EOS from Arista Networks, with a CVSS 3.1 base score of 7.4 out of 10. It can be exploited from the same local network by an unauthenticated attacker, without any action from a user. Affected EOS versions: 4.36.0 through 4.36.1F. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 0.17% 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
- Check which version of EOS you run against the affected versions below, and install the vendor's latest release.
- 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 | 4.36.0 through 4.36.1F | Not stated |
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
- NoneNothing can be modified.
- 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:N/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 | 7.4 | High | CNA (arista.com) |
Official description
On affected platforms running Arista EOS with IS-IS configured, an unauthenticated attacker who can inject a specially crafted IS-IS LSP PDU can cause the legitimate LSP to be unexpectedly purged from the IS-IS link-state database. This may result in traffic loss.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Improper Validation of Integrity Check Value
The product does not validate or incorrectly validates the integrity check values or checksums of a message.
How developers prevent this class of flaw
- The protocol specification describes the algorithm used for calculating the checksum. It is then a matter of implementing the calculation and verifying that the calculated checksum and the received checksum match.
More Improper Validation of Integrity Check Value vulnerabilities (CWE-354)
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 Improper Validation of Integrity Check Value vulnerabilities
- 8.8 High severity
- 9.1 Critical severity
- 9.0 Critical severity
- 8.6 High severity
- 7.5 High severity
- 7.5 High severity
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