Vulnerability Description
A Use After Free vulnerability in the chassis daemon (chassisd) of Juniper Networks Junos OS and Junos OS Evolved allows a network-based attacker authenticated with low privileges to cause a Denial-of-Service (DoS). When telemetry collectors are frequently subscribing and unsubscribing to sensors continuously over a long period of time, telemetry-capable processes like chassisd, rpd or mib2d will crash and restart, which - depending on the process - can cause a complete outage until the system has recovered. This issue affects: Junos OS: * all versions before 22.4R3-S8, * 23.2 versions before 23.2R2-S5, * 23.4 versions before 23.4R2; Junos OS Evolved: * all versions before 22.4R3-S8-EVO, * 23.2 versions before 23.2R2-S5-EVO, * 23.4 versions before 23.4R2-EVO.
CVSS Score
MEDIUM
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Juniper | Junos | < 22.4 |
| Juniper | Junos Os Evolved | < 22.4 |
Related Weaknesses (CWE)
References
- https://kb.juniper.net/JSA106021Vendor Advisory
- https://supportportal.juniper.net/JSA106021Vendor Advisory
FAQ
What is CVE-2026-21921?
CVE-2026-21921 is a vulnerability with a CVSS score of 6.5 (MEDIUM). A Use After Free vulnerability in the chassis daemon (chassisd) of Juniper Networks Junos OS and Junos OS Evolved allows a network-based attacker authenticated with low privileges to cause a Denial-of...
How severe is CVE-2026-21921?
CVE-2026-21921 has been rated MEDIUM with a CVSS base score of 6.5/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2026-21921?
Check the references section above for vendor advisories and patch information. Affected products include: Juniper Junos, Juniper Junos Os Evolved.