Vulnerability Description
A Double Free vulnerability in the flow processing daemon (flowd) of Juniper Networks Junos OS on SRX and MX Series allows an unauthenticated, network-based attacker to cause a Denial-of-Service (DoS). On all SRX and MX Series platforms, when during TCP session establishment a specific sequence of packets is encountered a double free happens. This causes flowd to crash and the respective FPC to restart. This issue affects Junos OS on SRX and MX Series: * all versions before 22.4R3-S7, * 23.2 versions before 23.2R2-S3, * 23.4 versions before 23.4R2-S4, * 24.2 versions before 24.2R2.
CVSS Score
HIGH
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Juniper | Junos | < 22.4 |
| Juniper | Mx10004 | - |
| Juniper | Mx10008 | - |
| Juniper | Mx2008 | - |
| Juniper | Mx2010 | - |
| Juniper | Mx2020 | - |
| Juniper | Mx204 | - |
| Juniper | Mx240 | - |
| Juniper | Mx304 | - |
| Juniper | Mx480 | - |
| Juniper | Mx960 | - |
| Juniper | Srx1500 | - |
| Juniper | Srx1600 | - |
| Juniper | Srx2300 | - |
| Juniper | Srx300 | - |
| Juniper | Srx320 | - |
| Juniper | Srx340 | - |
| Juniper | Srx345 | - |
| Juniper | Srx380 | - |
| Juniper | Srx4100 | - |
Related Weaknesses (CWE)
References
- https://kb.juniper.net/JSA106018Vendor Advisory
- https://supportportal.juniper.net/JSA106018Vendor Advisory
FAQ
What is CVE-2026-21918?
CVE-2026-21918 is a vulnerability with a CVSS score of 7.5 (HIGH). A Double Free vulnerability in the flow processing daemon (flowd) of Juniper Networks Junos OS on SRX and MX Series allows an unauthenticated, network-based attacker to cause a Denial-of-Service (DoS)...
How severe is CVE-2026-21918?
CVE-2026-21918 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-2026-21918?
Check the references section above for vendor advisories and patch information. Affected products include: Juniper Junos, Juniper Mx10004, Juniper Mx10008, Juniper Mx2008, Juniper Mx2010.