# CVE-2026-121287: Security Advisory 0221

Status: published. Published: 2026-11-10. Updated: 2026-11-13.

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.

## Remediation

- workaround: switch(config)# router rip
switch(config-router-rip)# shutdown
switch(config-router-rip)# end

Note: disabling RIP or changing network statements may withdraw routes and interrupt connectivity. Plan a change window, confirm alternate routing, and verify the resulting configuration and route behavior. (source: CNA: Arista)

## Affected products and versions

- Arista Networks / EOS: 4.37.0F (affected, custom); ≥ 4.36.0F; ≤ 4.36.2F (affected, custom); ≥ 4.35.0F; ≤ 4.35.6M (affected, custom); ≥ 4.34.0F; ≤ 4.34.8M (affected, custom); ≥ 4.33.0F; ≤ 4.33.10M (affected, custom); ≥ 4.32.0F; < 4.33.0F (affected, custom); ≥ 1.0.0; < 4.32.0F (affected, custom). Source: CNA: Arista; platforms: 710 Series, 720D Series, 720XP/722XPM Series, 750X Series, 7010TX Series, 7020R/R4 Series, 7130 Series running EOS, 7170 Series, 7050X3/X4 Series, 7060X/X2/X4/X5/X6/XE7 Series, 7260X/X3 Series, 7280R/R2/R3/R4 Series, 7300X/X3 Series, 7320X Series, 7358X4 Series, 7368X4 Series, 7388X5 Series, 7500R/R2/R3 Series, 7800R3/R4 Series, 7700R4 Series, AWE 5000 Series, AWE 7200R Series, CloudEOS, cEOS-lab, vEOS-lab, CloudVision eXchange, virtual or physical appliance

## Severity and prioritization

- CVSS 3.1: 8.8 (high); CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H; source: CNA: Arista

- CVSS 4.0: 7.7 (high); CVSS:4.0/AV:A/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:L/SA:N; source: CNA: Arista

- CVSS 4.0: 7.7 (high); CVSS:4.0/AV:A/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:L/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X; source: NVD: psirt@arista.com

- CVSS 3.1: 8.8 (high); CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H; source: NVD: psirt@arista.com

- CISA KEV: No listing in collected sources

- EPSS: 0.24% as of 2026-11-12; percentile 14.72%

- SSVC: exploitation none; automatable no; technical impact total; source ADP: CISA-ADP

- Weaknesses: CWE-124

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://www.arista.com/en/support/advisories-notices/security-advisory/25043-security-advisory-0221 (CNA: Arista; vendor-advisory)

- https://www.arista.com/en/support/advisories-notices/security-advisory/25043-security-advisory-0221 (psirt@arista.com)

## Provenance

- CNA: Arista: https://www.cve.org/CVERecord?id=CVE-2026-121287; retrieved 2026-11-13; source updated 2026-11-13

- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-121287; retrieved 2026-11-13; source updated 2026-11-13

- FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2026-121287; retrieved 2026-11-13; source updated Not reported

Revision: a47af84b25a76c0c2753dd0c0190f7721717fcc6b60e24eeeaacb7d07b0d12fb

Canonical: https://y2.dev/cve/CVE-2026-121287

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