An improper check for unusual or exceptional conditions (CWE-754) in the packet forwarding engine of Juniper Junos OS on QFX10000 Series devices leads to a denial-of-service vulnerability. In EVPN-VxLAN deployments, IPv6 multicast packets sent to non-IRB interfaces on spine switches are flooded endlessly among spine and ESI leaf switches, saturating links and impacting legitimate traffic. The vulnerability affects multiple Junos OS versions prior to specific patch releases. No official remediation level or patch links are provided in the source data. The CVSS 3.1 base score is 6.5 (medium severity) with attack vector adjacent, low attack complexity, no privileges required, no user interaction, and impact limited to availability.

The vulnerability allows an unauthenticated, adjacent attacker to cause a denial-of-service by flooding network links in an endless loop, disrupting legitimate traffic on QFX10000 Series devices running affected Junos OS versions. There is no impact on confidentiality or integrity reported. The DoS impact can degrade network availability and performance in EVPN-VxLAN environments.

Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. The affected versions are fixed in later releases as indicated by version boundaries, but no explicit patch or official fix details are provided in the source data. Operators should upgrade to versions 23.2R2-S7 or later for 23.2 releases, 23.4R2-S8 or later for 23.4 releases, 24.2R2-S4 or later for 24.2 releases, and 24.4R2-S4 or later for 24.4 releases to mitigate this issue. Versions after 24.4 are not affected due to discontinued support for QFX10000 on those versions.