Junos OS (SRX firewalls)
CVE-2026-21913: EX4000: A high volume of traffic destined to the device leads to a crash and restart
An Incorrect Initialization of Resource vulnerability in the Internal Device Manager (IDM) of Juniper Networks Junos OS on EX4000 models allows an unauthenticated, network-based attacker to cause a Denial-of-Service (DoS).
Published
Automatic summary from the vendor's CVE record. We haven't written a full analysis of this vulnerability yet.
Affected and fixed versions
| Product / branch | Fixed in |
|---|---|
| Junos OS (EX4000-48T, EX4000-48P, EX4000-48MP) 24.4 | 24.4R2 or later |
| Junos OS (EX4000-48T, EX4000-48P, EX4000-48MP) 25.2 | 25.2R1-S2, 25.2R2 or later |
| Junos OS (EX4000-48T, EX4000-48P, EX4000-48MP) 0 | Not affected |
Always confirm against the vendor advisory, which lists every fixed hotfix.
What it is
An Incorrect Initialization of Resource vulnerability in the Internal Device Manager (IDM) of Juniper Networks Junos OS on EX4000 models allows an unauthenticated, network-based attacker to cause a Denial-of-Service (DoS).
On EX4000 models with 48 ports (EX4000-48T, EX4000-48P, EX4000-48MP) a high volume of traffic destined to the device will cause an FXPC crash and restart, which leads to a complete service outage until the device has automatically restarted.
The following reboot reason can be seen in the output of 'show chassis routing-engine' and as a log message:
reason=0x4000002 reason_string=0x4000002:watchdog + panic with core dump
This issue affects Junos OS on EX4000-48T, EX4000-48P and EX4000-48MP:
- 24.4 versions before 24.4R2,
- 25.2 versions before 25.2R1-S2, 25.2R2.
This issue does not affect versions before 24.4R1 as the first Junos OS version for the EX4000 models was 24.4R1.
Workarounds
There are no known workarounds for this issue.
Exploitation
Juniper SIRT is not aware of any malicious exploitation of this vulnerability.
Sources
KEV status, EPSS score and vendor data refreshed automatically, last on 13 Oct 2026.