Junos OS (SRX firewalls)
CVE-2024-21605: SRX 300 Series: Specific link local traffic causes a control plane overload
An Exposure of Resource to Wrong Sphere vulnerability in the Packet Forwarding Engine (PFE) of Juniper Networks Junos OS on SRX 300 Series allows an unauthenticated, adjacent 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 (SRX 300 Series) 21.2R3-S3 | 21.2R3-S6 or later |
| Junos OS (SRX 300 Series) 22.1R3 | 22.1R3-S4 or later |
| Junos OS (SRX 300 Series) 22.2R2 | 22.2R3-S2 or later |
| Junos OS (SRX 300 Series) 22.3R2 | 22.3R3-S1 or later |
| Junos OS (SRX 300 Series) 22.4 | 22.4R2-S2, 22.4R3 or later |
| Junos OS (SRX 300 Series) 23.2 | 23.2R1-S1, 23.2R2 or later |
| Junos OS (SRX 300 Series) 21.4 | Not affected |
Always confirm against the vendor advisory, which lists every fixed hotfix.
What it is
An Exposure of Resource to Wrong Sphere vulnerability in the Packet Forwarding Engine (PFE) of Juniper Networks Junos OS on SRX 300 Series allows an unauthenticated, adjacent attacker to cause a Denial of Service (DoS).
Specific valid link-local traffic is not blocked on ports in STP blocked state but is instead sent to the control plane of the device. This leads to excessive resource consumption and in turn severe impact on all control and management protocols of the device.
This issue affects Juniper Networks Junos OS: * 21.2 version 21.2R3-S3 and later versions earlier than 21.2R3-S6; * 22.1 version 22.1R3 and later versions earlier than 22.1R3-S4; * 22.2 version
22.2R2
and later versions earlier than 22.2R3-S2; * 22.3 version
22.3R2
and later versions earlier than 22.3R3-S1;
- 22.4 versions earlier than 22.4R2-S2, 22.4R3;
- 23.2 versions earlier than 23.2R1-S1, 23.2R2.
This issue does not affect Juniper Networks Junos OS 21.4R1 and later versions of 21.4.
Am I affected?
To be affected by this vulnerability at least two interfaces need to be configured with an STP:
[ protocols (stp | mstp | rstp | vstp) interface <interface> ]
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.