CVE-2026-101980: CWE-191 Integer Underflow (Wrap or Wraparound) in Juniper Networks Junos OS

This vulnerability is an integer underflow (CWE-191) in the kernel of Juniper Networks Junos OS with Extended Echo configured. An unauthenticated attacker can exploit this flaw remotely over the network to trigger a kernel crash, resulting in denial of service. The vulnerability affects multiple version ranges of Junos OS prior to the indicated fixed releases. No known exploits in the wild have been reported. The CVSS v3.1 base score is 9.8, reflecting the critical impact and ease of exploitation without privileges or user interaction.

Successful exploitation results in a denial of service condition caused by a kernel crash. This disrupts network operations on affected Junos OS devices. The vulnerability impacts confidentiality, integrity, and availability as indicated by the CVSS vector, but the primary impact is availability loss due to the kernel crash.

Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. No official patch or workaround information is provided in the available data. Users should monitor Juniper Networks advisories for updates and apply patches promptly once available. Until then, consider disabling Extended Echo if feasible to reduce exposure.