Vulnerability Description
An Unchecked Return Value vulnerability in the DNS module of Juniper Networks Junos OS on SRX Series allows an unauthenticated, network-based attacker to cause a Denial-of-Service (DoS). If an SRX Series device configured for DNS processing, receives a specifically formatted DNS request flowd will crash and restart, which causes a service interruption until the process has recovered. This issue affects Junos OS on SRX Series: * 23.4 versions before 23.4R2-S5, * 24.2 versions before 24.2R2-S1, * 24.4 versions before 24.4R2. This issue does not affect Junos OS versions before 23.4R1.
CVSS Score
HIGH
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Juniper | Junos | 23.4 |
| Juniper | Srx1500 | - |
| Juniper | Srx1600 | - |
| Juniper | Srx2300 | - |
| Juniper | Srx300 | - |
| Juniper | Srx320 | - |
| Juniper | Srx340 | - |
| Juniper | Srx345 | - |
| Juniper | Srx380 | - |
| Juniper | Srx4100 | - |
| Juniper | Srx4120 | - |
| Juniper | Srx4200 | - |
| Juniper | Srx4300 | - |
| Juniper | Srx4600 | - |
| Juniper | Srx4700 | - |
| Juniper | Srx5400 | - |
| Juniper | Srx5600 | - |
| Juniper | Srx5800 | - |
Related Weaknesses (CWE)
References
- https://kb.juniper.net/JSA106020Vendor Advisory
- https://supportportal.juniper.net/JSA106020Vendor Advisory
FAQ
What is CVE-2026-21920?
CVE-2026-21920 is a vulnerability with a CVSS score of 7.5 (HIGH). An Unchecked Return Value vulnerability in the DNS module of Juniper Networks Junos OS on SRX Series allows an unauthenticated, network-based attacker to cause a Denial-of-Service (DoS). If an SRX...
How severe is CVE-2026-21920?
CVE-2026-21920 has been rated HIGH with a CVSS base score of 7.5/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2026-21920?
Check the references section above for vendor advisories and patch information. Affected products include: Juniper Junos, Juniper Srx1500, Juniper Srx1600, Juniper Srx2300, Juniper Srx300.