What is CVE-2026-121287?

CVE-2026-121287 is a high-severity vulnerability in Arista Networks Eos, classified under Buffer Underwrite. CVSS score: 8.8/10. Published 2026-11-10.

How severe is CVE-2026-121287?

High severity. CVSS v3 base score is 8.8 out of 10.

Vulnerability in Arista Networks Eos

CVE-2026-121287

An unauthenticated attacker on an adjacent network segment can send crafted RIPv2 packets to a RIP-enabled interface on the device to trigger the Rip agent crash without providing valid credentials. Repeated exploitation reliably interrupts routing service on the affected device, which may also disrupt routing for other devices that depend on it. In a worst-case scenario, the vulnerability may allow an attacker to execute arbitrary code on the affected device.

Published 2026-11-10.

CVSS v3 metric

CVSS v3 base score 8.8 (High). Vector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

EPSS exploit prediction

No EPSS score from FIRST.org yet. New CVEs usually get one within a few days; no score means no signal yet, not low risk. How EPSS works.

Affected products

Arista Networks Eos — versions 4.37.0F

Weakness classification (CWE)

CWE-124 — Buffer Underwrite

References

www.arista.com/en/support/advisories-notices/security-advisory/25043-security-a… (vendor-advisory)

Frequently asked questions

What is CVE-2026-121287?: CVE-2026-121287 is a high-severity vulnerability in Arista Networks Eos, classified under Buffer Underwrite. CVSS score: 8.8/10. Published 2026-11-10.
How severe is CVE-2026-121287?: High severity. CVSS v3 base score is 8.8 out of 10.