High · CVSS 7.7CVE-2026-121287

Security Advisory 0221CVE-2026-121287

Answer in brief

CVE-2026-121287 records a High severity (CVSS 7.7) vulnerability in Security Advisory 0221. The current sources do not mark it as known exploited. The current feed maps Arista Networks/EOS (generic). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Nov 10, 2026Updated Nov 10, 2026Source checked Nov 10, 2026First seen by HOL Nov 10, 2026Material review Nov 10, 2026

Upstream Advisory

Key facts

Risk: High · CVSS 7.7
Exploitation: Not marked as known exploited
Affected software: 1 mapped package or product
Fix availability: Not reported

Why this deserves its current priority

CVSS is 7.7. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps Arista Networks/EOS (generic). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
Arista Networks/EOSgeneric	4.37.0F \|\| >=4.36.0F <=4.36.2F \|\| >=4.35.0F <=4.35.6M \|\| >=4.34.0F <=4.34.8M \|\| >=4.33.0F <=4.33.10M \|\| >=4.32.0F <4.33.0F \|\| >=1.0.0 <4.32.0F	Not reported

Recommended response

Check inventory. Check lockfiles and deployed manifests for Arista Networks/EOS.
Review the reported fix. Source-reported 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.

Evidence timeline and material changes

Published upstream
Nov 10, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Nov 10, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Nov 10, 2026

Sources and claim methodology

Source referencearista.com

Upstream source description

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.

Quoted source text, attributed separately from HOL analysis.

Affected scope and exposure questions

The current feed maps Arista Networks/EOS (generic). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
Arista Networks/EOSgeneric	4.37.0F \|\| >=4.36.0F <=4.36.2F \|\| >=4.35.0F <=4.35.6M \|\| >=4.34.0F <=4.34.8M \|\| >=4.33.0F <=4.33.10M \|\| >=4.32.0F <4.33.0F \|\| >=1.0.0 <4.32.0F	Not reported

Recommended response

Check inventory. Check lockfiles and deployed manifests for Arista Networks/EOS.

Review the reported fix. Source-reported 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.

Sources and claim methodology

Upstream source description

Quoted source text, attributed separately from HOL analysis.