CVE-2026-21920
Severity CVSS v4.0:
HIGH
Type:
Unavailable / Other
Publication date:
15/01/2026
Last modified:
15/01/2026
Description
An Unchecked Return Value vulnerability in the DNS module of Juniper Networks Junos OS on SRX Series allows an unauthenticated, network-based attacker to cause a Denial-of-Service (DoS).<br />
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If an SRX Series device configured for DNS processing, receives a specifically formatted DNS request flowd will crash and restart, which causes a service interruption until the process has recovered.<br />
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This issue affects Junos OS on SRX Series:<br />
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* 23.4 versions before 23.4R2-S5,<br />
* 24.2 versions before 24.2R2-S1,<br />
* 24.4 versions before 24.4R2.<br />
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This issue does not affect Junos OS versions before 23.4R1.
Impact
Base Score 4.0
8.70
Severity 4.0
HIGH
Base Score 3.x
7.50
Severity 3.x
HIGH