The vulnerability is an improper validation of input consistency within the l2cpd process. It allows an adjacent unauthenticated Layer 2 attacker to send a crafted MVRP Ethernet frame to an MVRP‑enabled interface, causing the l2cpd process to terminate and resulting in a denial of service for Layer 2 control protocols such as MVRP, LACP, and others. An affected device experiences a loss of these control functions until the l2cpd process is restarted or the device is rebooted. The weakness is a classic example of CWE‑1288: Improper Validation of Consistency within Input.

The vulnerability affects Juniper Networks Junos OS and Junos OS Evolved. Firmware releases with known fixes 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 subsequent releases, as well as the corresponding Junos OS Evolved releases 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 subsequent releases. Devices running earlier releases that have not been rebuilt are potentially vulnerable.

The CVSS score of 7.1 indicates a high impact denial of service with an affected Availability metric. The EPSS score is not available, and the vulnerability is not listed in the CISA KEV catalog, suggesting that there is no documented exploitation yet. Nevertheless, the attack vector is local to the Layer 2 domain, meaning any device that can send unfiltered Ethernet frames to a Junos switch on the same network segment can attempt the exploit. Because the vulnerability requires no authentication and can be triggered by simple frame crafting, the risk remains significant for environments that rely on contiguous, unmanaged Layer 2 segments and have MVRP enabled.