High priorityDisclosed

Advisory · CVE-2026-101943

Input validation flaw in Junos rpd lets a crafted EVPN update crash the daemon

An improper input validation vulnerability in the routing protocol daemon (rpd) of Junos OS and Junos OS Evolved lets an unauthenticated network attacker cause a denial of service via a crafted BGP EVPN update message. Juniper rates it CVSS 4.0 8.7 (CVSS 3.1 7.5).

Advisory published October 14, 2026Independent summary
Vendor
Juniper Networks
Product
Junos OS
Identifier / CWE
CVE-2026-101943
CWE-20
Action timing
Immediate
ELI5

Explain it like I’m five

The daemon trusts the shape of an EVPN update more than it should, and a crafted one knocks it over.

SIMPLIFIED_ATTACK_PATH03 STEPS
  1. 01Trigger input

    An attacker sends the crafted protocol traffic described for CVE-2026-101943.

  2. 02Weakness trips

    The daemon mishandles the input through the improper input validation weakness.

  3. 03Impact lands

    The routing or control-plane daemon crashes or misbehaves as described.

What happened

Juniper disclosed CVE-2026-101943 in its October 2026 security release: an improper input validation vulnerability (CWE-20) in rpd. A crafted BGP EVPN update message can deny service on Junos OS and Junos OS Evolved.

Juniper’s JSA112187 lists the affected service releases and the October 2026 service release thresholds that carry the fix. Match your exact release to the advisory rather than guessing here.

What to do

  1. Inventory every Junos OS deployment, including test, training, and individually managed instances.
  2. Apply the vendor fix or upgrade exactly as directed in the linked vendor bulletin or advisory.
  3. Restrict network access to Junos OS while remediation is underway, especially for internet-facing instances.
  4. Review application and server logs for rpd crashes following unusual BGP EVPN update messages.
  5. Check for accounts, content, or configuration created outside normal change processes, and rotate exposed credentials where access cannot be ruled out.
  6. Verify the deployed version or patch level after remediation.

Management note

This is one of several EVPN rpd crashes in the same release. A single fabric-wide patch window clears the set.