High priorityDisclosed

Advisory · CVE-2026-102029

NULL pointer flaw in Junos rpd lets MSDP or PIM policy crash the daemon

A NULL pointer dereference vulnerability in the routing protocol daemon (rpd) of Junos OS and Junos OS Evolved lets an unauthenticated configured MSDP peer or adjacent PIM sender cause a denial of service via an MSDP or PIM policy that uses AS-path expansion. 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-2026-102029
CWE-476
Action timing
Immediate
ELI5

Explain it like I’m five

A multicast policy that expands AS paths meets traffic it did not expect, and the daemon dereferences nothing at all.

SIMPLIFIED_ATTACK_PATH03 STEPS
  1. 01Trigger input

    An attacker sends the crafted protocol traffic described for CVE-2026-102029.

  2. 02Weakness trips

    The daemon mishandles the input through the null pointer dereference weakness.

  3. 03Impact lands

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

What happened

Juniper disclosed CVE-2026-102029 in its October 2026 security release: a NULL pointer dereference (CWE-476) in rpd. An unauthenticated configured MSDP peer or adjacent PIM sender can deny service via an MSDP or PIM policy that uses AS-path expansion.

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 tied to MSDP or PIM activity on devices whose policies use AS-path expansion.
  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

Multicast is a small blast radius until it is the video or market-data feed. Patch the MSDP/PIM edge.