Executive brief
A vulnerability in Juniper Networks' networking software could allow a user with low-level access to crash a critical system process. This affects EX, QFX, and MX series hardware, causing a temporary disruption to all Layer 2 network services until the system automatically restarts. While the system recovers on its own, it can lead to intermittent network outages and operational instability.
Technical details
A 'Return of Pointer Value Outside of Expected Range' vulnerability (CWE-466) exists in the fileio library of Juniper Networks Junos OS and Junos OS Evolved. On EX, QFX, and MX Series devices, a local attacker with low privileges can trigger this flaw by executing a specific 'show l2-learning' command. This action causes the Layer 2 Address Learning Daemon (l2ald) to crash, resulting in a temporary Denial-of-Service (DoS) for all Layer 2 services until the process automatically restarts. The issue is resolved in Junos OS versions 23.2R2-S7, 23.4R2-S7, 24.2R2, 24.4R1-S2 and their respective Evolved counterparts.
Affected products
- Juniper Networks Junos OS All versions before 23.2R2-S7, 23.4 versions before 23.4R2-S7, 24.2 versions before 24.2R2, 24.4 versions before 24.4R1-S2
- Juniper Networks Junos OS Evolved All versions before 23.2R2-S7-EVO, 23.4 versions before 23.4R2-S8-EVO, 24.2 versions before 24.2R2-EVO, 24.4 versions before 24.4R1-S3-EVO
Timeline
- 2026-07-09: advisory
- 2026-07-09: disclosed