A stack-based buffer overflow in the httpd process of Juniper Networks Junos OS and Junos OS Evolved allows an unauthenticated network attacker to execute arbitrary code and cause a denial of service when a J‑Web virtual‑domain is configured. The vulnerability is a classic CWE‑121 flaw, where input data overflows a local stack buffer, giving attackers control of program flow.

The affected products are Juniper Networks Junos OS and Juniper Networks Junos OS Evolved. Vulnerable releases include Junos OS 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; and Junos OS Evolved 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 9.3 indicates critical severity, while no EPSS score is available and the vulnerability is not listed in the CISA KEV catalog. The attack is likely to be launched over the network by an unauthenticated attacker who can send crafted traffic to the J‑Web virtual‑domain, exploiting the buffer overflow to gain code execution and possibly bring down the httpd process. Given the high CVSS, the overall risk to systems running the vulnerable releases is significant.