High priorityDisclosed

Advisory · CVE-2026-102064

Reachable assertion in Junos rpd lets an eBGP peer crash it with MCAST-VPN updates

A reachable assertion vulnerability in the routing protocol daemon (rpd) of Junos OS and Junos OS Evolved lets an attacker cause an rpd crash via malformed BGP MCAST-VPN updates from a configured eBGP peer. 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-2026-102064
CWE-617
Action timing
Immediate
ELI5

Explain it like I’m five

A malformed multicast VPN update hits an assertion the developers assumed was unreachable, and the daemon restarts.

SIMPLIFIED_ATTACK_PATH03 STEPS
  1. 01Trigger input

    An attacker sends the crafted protocol traffic described for CVE-2026-102064.

  2. 02Weakness trips

    The daemon mishandles the input through the reachable assertion weakness.

  3. 03Impact lands

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

What happened

Juniper disclosed CVE-2026-102064 in its October 2026 security release: a reachable assertion vulnerability (CWE-617) in rpd. Malformed BGP MCAST-VPN updates from a configured eBGP peer can crash rpd 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 assertion failures following MCAST-VPN updates from eBGP peers.
  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

Assertions are tripwires, not fixes. Patch, and note that three assertion crashes shipped in this one Juniper release.