Junos OS (SRX firewalls)
CVE-2024-21586: SRX Series and NFX Series: Specific valid traffic leads to a PFE crash
An Improper Check for Unusual or Exceptional Conditions vulnerability in the Packet Forwarding Engine (PFE) of Juniper Networks Junos OS on SRX Series and NFX Series 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 (SRX Series) 0 | Not affected |
| Junos OS (SRX Series) 21.4 | 21.4R3-S7.9 or later |
| Junos OS (SRX Series) 22.1 | 22.1R3-S5.3 or later |
| Junos OS (SRX Series) 22.2 | 22.2R3-S4.11 or later |
| Junos OS (SRX Series) 22.3 | 22.3R3 or later |
| Junos OS (SRX Series) 22.4 | 22.4R3 or later |
| Junos OS (NFX Series) 0 | Not affected |
| Junos OS (NFX Series) 21.4 | 21.4R3-S8 or later |
| Junos OS (NFX Series) 22.1 | See the advisory |
| Junos OS (NFX Series) 22.2 | 22.2R3-S5 or later |
| Junos OS (NFX Series) 22.3 | 22.3R3 or later |
| Junos OS (NFX Series) 22.4 | 22.4R3 or later |
Always confirm against the vendor advisory, which lists every fixed hotfix.
What it is
An Improper Check for Unusual or Exceptional Conditions vulnerability in the Packet Forwarding Engine (PFE) of Juniper Networks Junos OS on SRX Series and NFX Series allows an unauthenticated, network-based attacker to cause a Denial-of-Service (DoS).
If an affected device receives specific valid traffic destined to the device, it will cause the PFE to crash and restart. Continued receipt and processing of this traffic will create a sustained DoS condition.
This issue affects Junos OS on SRX Series:
- 21.4 versions before 21.4R3-S7.9,
- 22.1 versions before 22.1R3-S5.3,
- 22.2 versions before 22.2R3-S4.11,
- 22.3 versions before 22.3R3,
- 22.4 versions before 22.4R3.
This issue affects Junos OS on NFX Series:
- 21.4 versions before 21.4R3-S8,
- 22.1 versions after 22.1R1,
- 22.2 versions before 22.2R3-S5,
- 22.3 versions before 22.3R3,
- 22.4 versions before 22.4R3.
Junos OS versions prior to 21.4R1 are not affected by this issue.
Workarounds
There are no known workarounds for this issue.
Exploitation
Juniper SIRT is not aware of any malicious exploitation of this vulnerability. However, multiple occurrences of this issue have been reported in production.
Sources
KEV status, EPSS score and vendor data refreshed automatically, last on 13 Oct 2026.