Junos OS (SRX firewalls)
CVE-2023-36842: jdhcpd will hang on receiving a specific DHCP packet
An Improper Check for Unusual or Exceptional Conditions vulnerability in Juniper DHCP Daemon (jdhcpd) of Juniper Networks Junos OS allows an adjacent, unauthenticated attacker to cause the jdhcpd to consume all the CPU cycles resulting in 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, EX Series) 0 | 20.4R3-S9 or later |
| Junos OS (MX Series, EX Series) 21.2 | 21.2R3-S7 or later |
| Junos OS (MX Series, EX Series) 21.3 | 21.3R3-S5 or later |
| Junos OS (MX Series, EX Series) 21.4 | 21.4R3-S5 or later |
| Junos OS (MX Series, EX Series) 22.1 | 22.1R3-S4 or later |
| Junos OS (MX Series, EX Series) 22.2 | 22.2R3-S3 or later |
| Junos OS (MX Series, EX Series) 22.3 | 22.3R3-S2 or later |
| Junos OS (MX Series, EX Series) 22.4 | 22.4R2-S2, 22.4R3 or later |
| Junos OS (MX Series, EX Series) 23.2 | 23.2R2 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 Juniper DHCP Daemon (jdhcpd) of Juniper Networks Junos OS allows an adjacent, unauthenticated attacker to cause the jdhcpd to consume all the CPU cycles resulting in a Denial of Service (DoS).
On Junos OS devices with forward-snooped-client configured, if an attacker sends a specific DHCP packet to a non-configured interface, this will cause an infinite loop. The DHCP process will have to be restarted to recover the service.
This issue affects:
Juniper Networks Junos OS
- All versions earlier than 20.4R3-S9;
- 21.2 versions earlier than 21.2R3-S7;
- 21.3 versions earlier than 21.3R3-S5;
- 21.4 versions earlier than 21.4R3-S5;
- 22.1 versions earlier than 22.1R3-S4;
- 22.2 versions earlier than 22.2R3-S3;
- 22.3 versions earlier than 22.3R3-S2;
- 22.4 versions earlier than 22.4R2-S2, 22.4R3;
- 23.2 versions earlier than 23.2R2.
Am I affected?
To be affected a device must be configured with:
[ forwarding-options dhcp-relay group <group-name> interface ... ] or
[ system services dhcp-local-server group <group-name> 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.