A stack‑based buffer overflow in the l2cpd daemon of Juniper Networks Junos OS and Junos OS Evolved causes a denial of service in Layer 2 control‑plane processing when LLDP packets are received on an interface that has LLDP enabled. The vulnerability allows an unauthenticated adjacent attacker to trigger the overflow by sending crafted LLDP messages, leading to abnormal termination of the l2cpd service and disrupting LLDP as well as other Layer 2 control protocols across the device. The weakness corresponds to CWE‑121.

Affected products are Juniper Networks Junos OS and Junos OS Evolved. Versions impacted include Junos OS releases 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. For Junos OS Evolved, the affected releases are 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.

The CVSS score of 8.7 categorizes this flaw as high severity. The likely attack vector is local on the same network segment, based on the description that the vulnerability is exploitable by an unauthenticated adjacent attacker when LLDP is enabled. The exploit requires no credentials or privileged access, making it relatively low complexity but potentially impactful if the device processes LLDP traffic. The event would disrupt multiple Layer 2 control protocols and could impair network connectivity, though it does not directly breach confidentiality or integrity. The vulnerability is not listed in the KEV catalog and no EPSS value is available, but the high CVSS score and local reach suggest the risk warrants prompt attention.