Product:
Junos OS Evolved
Summary
An Incorrect Calculation vulnerability in the Layer 2 Control Protocol Daemon of Juniper Networks Junos OS Evolved allows an unauthenticated network-adjacent attacker to cause the learning of new MACs over label-switched interfaces to stop while generating a flood of logs. This results in high CPU usage, impacting the performance of the affected systems.
Details
| Severity | Base Score | CVE |
|---|---|---|
| HIGH | 7.1 | CVE-2026-21911 |
Exploitation
To exploit this vulnerability, an attacker on the adjacent network can repeatedly flap the management interface, which triggers the vulnerability. This action leads to the system ceasing to learn new MAC addresses, causing a significant increase in log generation and CPU usage, potentially leading to denial of service.
Affected Products
- All versions before 21.4R3-S7-EVO
- From 22.2 before 22.2R3-S4-EVO
- From 22.3 before 22.3R3-S3-EVO
- From 22.4 before 22.4R3-S2-EVO
- From 23.2 before 23.2R2-S1-EVO
- From 23.4 before 23.4R1-S2-EVO
- 23.4R2-EVO
Mitigation
To mitigate this vulnerability, it is recommended to upgrade to the latest versions of Junos OS Evolved that are not affected by this issue. Regular monitoring of system logs and network traffic can also help in identifying potential exploitation attempts.