The flaw is an improper validation of a specified quantity in input to the routing protocol daemon (rpd), which is triggered by an unauthenticated IS‑IS peer. When BIER is enabled over IS‑IS on a Junos OS Evolved PTX Series device, the malformed input causes rpd to crash, leading to a denial of service. This results in loss of routing functionality and overall network availability for the affected host. The weakness is catalogued as CWE‑1284.

The vulnerability affects Juniper Networks Junos OS Evolved on PTX Series devices. It applies to 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.

The CVSS score of 7.1 indicates moderate‑to‑high severity. An EPSS score of <1% indicates a low probability of exploitation; however, the exact likelihood remains uncertain, and current information does not indicate existing exploits, so an attacker would need to establish an IS‑IS peer relationship and enable BIER over IS‑IS to trigger the vulnerability. The vulnerability is not listed in the CISA KEV catalog, indicating no confirmed active exploits at the time of this analysis. Even without active exploitation, the crash, making the risk significant for exposed or critical infrastructure.