Junos OS (SRX firewalls)
CVE-2024-21593: MX Series with MPC10, MPC11, LC9600, and MX304: A specific MPLS packet will cause a PFE crash
An Improper Check or Handling of Exceptional Conditions vulnerability in the Packet Forwarding Engine (PFE) of Juniper Networks Junos OS and Junos OS Evolved 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 (MX Series with MPC10, MPC11, LC9600, MX304) 21.4R3 | 21.4R3-S5 or later |
| Junos OS (MX Series with MPC10, MPC11, LC9600, MX304) 22.1 | Not affected |
| Junos OS (MX Series with MPC10, MPC11, LC9600, MX304) 22.2R2 | 22.2R3-S2 or later |
| Junos OS (MX Series with MPC10, MPC11, LC9600, MX304) 22.3R1 | 22.3R2-S2 or later |
| Junos OS (MX Series with MPC10, MPC11, LC9600, MX304) 22.3R3 | 22.3R3-S1 or later |
| Junos OS (MX Series with MPC10, MPC11, LC9600, MX304) 22.4R1 | 22.4R2-S2, 22.4R3 or later |
| Junos OS (MX Series with MPC10, MPC11, LC9600, MX304) 23.2 | 23.2R1-S1, 23.2R2 or later |
Always confirm against the vendor advisory, which lists every fixed hotfix.
What it is
An Improper Check or Handling of Exceptional Conditions vulnerability in the Packet Forwarding Engine (PFE) of Juniper Networks Junos OS and Junos OS Evolved allows an unauthenticated, adjacent attacker to cause a Denial of Service (DoS).
If an attacker sends a specific MPLS packet, which upon processing, causes an internal loop, that leads to a PFE crash and restart. Continued receipt of these packets leads to a sustained Denial of Service (DoS) condition.
Circuit cross-connect (CCC) needs to be configured on the device for it to be affected by this issue.
This issue only affects MX Series with MPC10, MPC11, LC9600, and MX304.
This issue affects: Juniper Networks Junos OS 21.4 versions from 21.4R3 earlier than 21.4R3-S5; 22.2 versions from 22.2R2 earlier than 22.2R3-S2; 22.3 versions from 22.3R1 earlier than 22.3R2-S2; 22.3 versions from 22.3R3 earlier than 22.3R3-S1 22.4 versions from 22.4R1 earlier than 22.4R2-S2, 22.4R3; 23.2 versions earlier than 23.2R1-S1, 23.2R2.
Am I affected?
To be affected by this issue, the following configuration is required on the device: [ encapsulation ethernet-ccc ]
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.