An attacker on the same local network can trigger a denial of service by sending a malformed ICCP peer message to the l2ald process when Multichassis Link Aggregation (MC-LAG) interface‑bridge (IRB) MAC synchronization is enabled. The vulnerability is a reachable assertion that can be satisfied with crafted traffic, causing the device to crash and halt networking services. This leads to a loss of connectivity and operational disruption, affecting availability but not compromising confidentiality or integrity.

The flaw affects Juniper Networks' Junos OS and Junos OS Evolved. Vulnerable releases include Junos OS 23.2R2-S7.7, 23.4R2-S8.13, 24.2R2-S5.5, 24.4R2-S5, 25.2R2-S2, 25.4R1-S3, 25.4R2, 26.2R1-S2, 26.2R2, 26.4R1 and all later releases, as well as Junos OS Evolved 23.2R2-S7.7-EVO, 23.4R2-S8.11-EVO, 24.2R2-S5.6-EVO, 24.4R2-S5-EVO, 25.2R2-S2-EVO, 25.2X100-D35-EVO, 25.4R1-S3-EVO, 25.4R2-EVO, 25.4X300-D40-EVO, 26.2R1-S2-EVO, 26.2R2-EVO, 26.4R1-EVO and all later releases.

The CVSS score of 7.1 indicates high severity. EPSS is not available, so the public evidence of exploitation is unknown, and the vulnerability is not listed in CISA KEV, implying no confirmed exploits in the wild. The likely attack vector is a local attacker sharing the network segment, who can send the triggering ICCP peer message. Successful exploitation requires that MC‑LAG IRB MAC synchronization is configured, a condition that mitigates the risk if the feature is not deployed.