CVE-2021-0270

Summary

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 Software

VendorProductVersion RangeStatus
Juniper NetworksJunos OS18.1R2 < 18.1*affected

Weaknesses

  • CWE-362: CWE-362 Race Condition (Concurrent Execution using Shared Resource with Improper Synchronization)
  • CWE-416: CWE-416 Use After Free

Workarounds

If you are susceptible to this issue and unable to upgrade to software with the fix, you can deploy a workaround by disabling the “inline-flow” feature.

To check for use and to disable the “inline-jflow” service on a device, see https://www.juniper.net/documentation/en_US/junos/topics/task/configuration/inline-flow-monitoring-ptx.html for additional details.

Removing “inline-jflow” takes effect immediately and there is no need to restart the FPCs or the router. Once the feature is removed, the router no longer provides traffic data to the flow collector.

ADP Enrichment

CVE Program Container

Additional References

References