CVE-2021-0270

Junos OS: PTX Series, QFX10K Series: A PTX/QFX FPC may restart unexpectedly with the "inline-Jflow" feature enabled on a large-scale deployment

MEDIUM
5.9
CVSS Score
Published: April 22, 2021 at 07:37 PM UTC
Updated: June 17, 2026 at 03:29 AM UTC
13 products affected across 2 vendorsJunosQfx10008Qfx10016

Using Junos OS by Juniper Networks?

Get instant alerts when new vulnerabilities affect Junos OS - before attackers find them.

Real-time alertsTrack your software stackFree plan available
Severity
MEDIUM5.9
Exploit prediction
EPSS 0.7%

Description

On PTX Series and QFX10k Series devices with the "inline-jflow" feature enabled, a use after free weakness in the Packet Forwarding Engine (PFE) microkernel architecture of Juniper Networks Junos OS may allow an attacker to cause a Denial of Service (DoS) condition whereby one or more Flexible PIC Concentrators (FPCs) may restart. As this is a race condition situation this issue become more likely to be hit when network instability occurs, such as but not limited to BGP/IGP reconvergences, and/or further likely to occur when more active "traffic flows" are occurring through the device. When this issue occurs, it will cause one or more FPCs to restart unexpectedly. During FPC restarts core files will be generated. While the core file is generated traffic will be disrupted. Sustained receipt of large traffic flows and reconvergence-like situations may sustain the Denial of Service (DoS) situation. This issue affects: Juniper Networks Junos OS: 18.1 version 18.1R2 and later versions prior to 18.1R3-S10 on PTX Series, QFX10K Series.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Affected range stops below 18.1*, so it looks safe — our inference, not a vendor statement
juniper-ptx1000 (environment) · juniper-ptx10001-36mr (environment) · juniper-ptx10002 (environment) · juniper-ptx10003 (environment) · juniper-ptx10004 (environment) · juniper-ptx10008 (environment) · juniper-ptx10016 (environment) · juniper-ptx3000 (environment) · juniper-ptx5000 (environment) · juniper-qfx10002 (environment) · juniper-qfx10008 (environment) · juniper-qfx10016 (environment)
All versions
All versions
All versions
All versions
All versions
All versions
All versions
All versions
All versions

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

CVSS

Attack Vector
NETWORK
Complexity
HIGH
Privileges
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
NONE
Availability
HIGH
Vector?

Quick Info

StatusMODIFIED
CWE
CWE-362CWE-416

Get alerted

Stop reading CVE feeds looking for your own stack

Track the products you run and VulnTracker tells you when a new CVE affects them — with what is known about fixing it, and nothing about the rest.

Free plan, no card