CVE-2026-21921
BaseFortify
Publication date: 2026-01-15
Last updated on: 2026-01-15
Assigner: Juniper Networks, Inc.
Description
Description
CVSS Scores
EPSS Scores
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Meta Information
Affected Vendors & Products
| Vendor | Product | Version / Range |
|---|---|---|
| juniper_networks | junos_os | to 22.4R3-S8 (exc) |
| juniper_networks | junos_os | to 23.2R2-S5 (exc) |
| juniper_networks | junos_os | to 23.4R2 (exc) |
| juniper_networks | junos_os_evolved | to 22.4R3-S8-EVO (exc) |
| juniper_networks | junos_os_evolved | to 23.2R2-S5-EVO (exc) |
| juniper_networks | junos_os_evolved | to 23.4R2-EVO (exc) |
Helpful Resources
Exploitability
| CWE ID | Description |
|---|---|
| CWE-416 | The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory "belongs" to the code that operates on the new pointer. |
Attack-Flow Graph
AI Powered Q&A
Can you explain this vulnerability to me?
This vulnerability is a Use After Free issue in the chassis daemon (chassisd) of Juniper Networks Junos OS and Junos OS Evolved. It allows a network-based attacker with low privileges to cause a Denial-of-Service (DoS) by causing telemetry-capable processes like chassisd, rpd, or mib2d to crash and restart when telemetry collectors frequently subscribe and unsubscribe to sensors over a long period.
How can this vulnerability impact me? :
The impact of this vulnerability is a Denial-of-Service (DoS) condition. When exploited, it can cause critical telemetry-capable processes to crash and restart, potentially leading to a complete outage until the system recovers.
What immediate steps should I take to mitigate this vulnerability?
To mitigate this vulnerability, you should upgrade your Junos OS or Junos OS Evolved to a fixed version. Specifically, update to at least version 22.4R3-S8, 23.2R2-S5, or 23.4R2 (or their EVO equivalents) or later, as all earlier versions are affected. Avoid frequent subscribing and unsubscribing to telemetry sensors to reduce the risk of triggering the issue until the update is applied.