CVE-2026-101990: CWE-121 Stack-based Buffer Overflow in Juniper Networks Junos OS

This vulnerability (CVE-2026-101990) is a stack-based buffer overflow in the routing protocol daemon (rpd) component of Juniper Networks Junos OS and Junos OS Evolved. A remote BGP peer configured with the ability to send flow-spec updates can trigger this overflow by sending a flow-spec update that is selected for re-advertisement. On Junos OS, this can lead to remote code execution; on Junos OS Evolved, it causes an rpd crash. The vulnerability affects a broad range of versions across multiple Junos OS and Junos OS Evolved releases, as detailed by the affected version ranges. The CVSS 3.1 vector indicates a critical severity with full impact on confidentiality, integrity, and availability without requiring privileges or user interaction.

Successful exploitation allows a remote attacker, acting as a configured BGP peer, to cause a denial of service by crashing the routing protocol daemon or achieve remote code execution on Junos OS. This can lead to significant network disruption and potential compromise of the affected device. The vulnerability impacts confidentiality, integrity, and availability of the system.

Patch status is not explicitly confirmed in the provided data. Users should consult the official Juniper Networks security advisory for CVE-2026-101990 to obtain the latest patch or mitigation instructions. Until patches are applied, restricting or monitoring BGP peers and flow-spec updates may reduce exposure. No vendor advisory content was provided to indicate that no action is required or that the issue is already mitigated.