CVE-2026-21912
Severity CVSS v4.0:
MEDIUM
Type:
Unavailable / Other
Publication date:
15/01/2026
Last modified:
15/01/2026
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 &#39;show system firmware&#39; CLI command to cause an LC480 or LC2101 line card to reset.<br />
<br />
On MX10k Series systems with LC480 or LC2101 line cards, repeated execution of the &#39;show system firmware&#39; 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: <br />
<br />
<br />
<br />
* all versions before 21.2R3-S10, <br />
* from 21.4 before 21.4R3-S9, <br />
* from 22.2 before 22.2R3-S7, <br />
* from 22.4 before 22.4R3-S6, <br />
* from 23.2 before 23.2R2-S2, <br />
* from 23.4 before 23.4R2-S3, <br />
* from 24.2 before 24.2R2.
Impact
Base Score 4.0
6.80
Severity 4.0
MEDIUM
Base Score 3.x
5.50
Severity 3.x
MEDIUM