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Description

A Time-of-check Time-of-use (TOCTOU) Race Condition vulnerability in the method to collect FPC Ethernet firmware statistics of Juniper Networks Junos OS on MX10k Series allows a local, low-privileged attacker executing the 'show system firmware' CLI command to cause an LC480 or LC2101 line card to reset. On MX10k Series systems with LC480 or LC2101 line cards, repeated execution of the 'show system firmware' CLI command can cause the line card to crash and restart. Additionally, some time after the line card crashes, chassisd may also crash and restart, generating a core dump.This issue affects Junos OS on MX10k Series: * all versions before 21.2R3-S10, * from 21.4 before 21.4R3-S9, * from 22.2 before 22.2R3-S7, * from 22.4 before 22.4R3-S6, * from 23.2 before 23.2R2-S2, * from 23.4 before 23.4R2-S3, * from 24.2 before 24.2R2.

PUBLISHED Reserved 2026-01-05 | Published 2026-01-15 | Updated 2026-01-15 | Assigner juniper




MEDIUM: 5.5CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

MEDIUM: 6.8CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:L/AU:Y/R:A/RE:M/U:Amber

Problem types

CWE-367 Time-of-check Time-of-use (TOCTOU) Race Condition

Product status

Default status
unaffected

Any version before 21.2R3-S10
affected

21.4 (semver) before 21.4R3-S9
affected

22.2 (semver) before 22.2R3-S7
affected

22.4 (semver) before 22.4R3-S6
affected

23.2 (semver) before 23.2R2-S2
affected

23.4 (semver) before 23.4R2-S3
affected

24.2 (semver) before 24.2R2
affected

References

supportportal.juniper.net/JSA106011 vendor-advisory

kb.juniper.net/JSA106011 vendor-advisory

cve.org (CVE-2026-21912)

nvd.nist.gov (CVE-2026-21912)

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