CVE-2026-21912

Name of the Vulnerable Software and Affected Versions Juniper Networks Junos OS on MX10k Series versions prior to 21.2R3-S10 Juniper Networks Junos OS on MX10k Series versions 21.4 before 21.4R3-S9 Juniper Networks Junos OS on MX10k Series versions 22.2 before 22.2R3-S7 Juniper Networks Junos OS on MX10k Series versions 22.4 before 22.4R3-S6 Juniper Networks Junos OS on MX10k Series versions 23.2 before 23.2R2-S2 Juniper Networks Junos OS on MX10k Series versions 23.4 before 23.4R2-S3 Juniper Networks Junos OS on MX10k Series version 24.2 before 24.2R2

Description A Time-of-check Time-of-use (TOCTOU) race condition exists in the method used to collect FPC Ethernet firmware statistics. This affects MX10k Series devices. A local attacker with low privileges, executing the 'show system firmware' command-line interface (CLI) command, can cause an LC480 or LC2101 line card to reset. Repeated execution of the 'show system firmware' CLI command can lead to a line card crash and restart. Following the line card crash, the chassisd process may also crash and restart, generating a core dump.

Recommendations Versions prior to 21.2R3-S10 should be updated. Versions 21.4 before 21.4R3-S9 should be updated. Versions 22.2 before 22.2R3-S7 should be updated. Versions 22.4 before 22.4R3-S6 should be updated. Versions 23.2 before 23.2R2-S2 should be updated. Versions 23.4 before 23.4R2-S3 should be updated. Version 24.2 before 24.2R2 should be updated.