A Time-of-check Time-of-use (TOCTOU) Race Condition vulnerability in telemetry processing of Juniper Networks Junos OS allows a network-based authenticated attacker to flood the system with multiple telemetry requests, causing the Junos Kernel Debugging Streaming Daemon (jkdsd) process to crash, leading to a Denial of Service (DoS). Continued receipt and processing of telemetry requests will repeatedly crash the jkdsd process and sustain the Denial of Service (DoS) condition.

This issue is seen on all Junos platforms. The crash is triggered when multiple telemetry requests come from different collectors. As the load increases, the Dynamic Rendering Daemon (drend) decides to defer processing and continue later, which results in a timing issue accessing stale memory, causing the jkdsd process to crash and restart.

Note: jkdsd is not shipped with SRX Series devices and therefore are not affected by this vulnerability. This issue affects:

Juniper Networks Junos OS:

• 20.4 versions prior to 20.4R3-S9;
• 21.1 versions 21.1R1 and later;
• 21.2 versions prior to 21.2R3-S6;
• 21.3 versions prior to 21.3R3-S5;
• 21.4 versions prior to 21.4R3-S5;
• 22.1 versions prior to 22.1R3-S4;
• 22.2 versions prior to 22.2R3-S2;
• 22.3 versions prior to 22.3R2-S1, 22.3R3-S1;
• 22.4 versions prior to 22.4R2-S2, 22.4R3;
• 23.1 versions prior to 23.1R2.

This issue does not affect Juniper Networks Junos OS versions prior to 19.4R1.