Race Condition Vulnerability in Juniper Networks Junos OS on MX10k Series
CVE-2026-21912

6.8MEDIUM

Key Information:

Vendor

Juniper Networks
Status
Junos Os
Vendor
CVE Published:
15 January 2026

Badges

👾 Exploit Exists

What is CVE-2026-21912?

A Time-of-check Time-of-use (TOCTOU) race condition vulnerability exists in the way Juniper Networks' Junos OS handles firmware statistics collection on MX10k Series systems. A local, low-privileged attacker can exploit this by repeatedly executing the 'show system firmware' CLI command, potentially causing the LC480 or LC2101 line card to crash and restart. This behavior may also lead to the chassisd process crashing and generating a core dump following the line card's failure. This vulnerability affects several versions of Junos OS on MX10k Series systems, necessitating prompt attention to secure network environments.

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Affected Version(s)

Junos OS MX10k Series 0 < 21.2R3-S10

Junos OS MX10k Series 21.4 < 21.4R3-S9

Junos OS MX10k Series 22.2 < 22.2R3-S7

References

https://supportportal.juniper.net/JSA106011
vendor-advisory
https://kb.juniper.net/JSA106011
vendor-advisory

CVSS V4

Score:
6.8
Severity:
MEDIUM
Confidentiality:
None
Integrity:
None
Availability:
High
Attack Vector:
Local
Attack Complexity:
Low
Attack Required:
None
Privileges Required:
Undefined
User Interaction:
None

Timeline

  • 👾

    Exploit known to exist

  • Vulnerability published

  • Vulnerability Reserved

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