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).




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.

This issue affects Junos OS on SRX Series:



* 23.4 versions before 23.4R2-S5,
* 24.2 versions before 24.2R2-S1,
* 24.4 versions before 24.4R2.






This issue does not affect Junos OS versions before 23.4R1.

Metrics

Attack Vector Network

Attack Complexity Low

Privileges Required None

Attack Requirements None

User Interaction None

Vulnerable System Confidentiality Impact None

Vulnerable System Integrity Impact None

Vulnerable System Availability Impact High

Subsequent System Confidentiality Impact None

Subsequent System Integrity Impact None

Subsequent System Availability Impact Low

Attack Vector Network

Attack Complexity Low

Privileges Required None

Scope Unchanged

Confidentiality Impact None

Integrity Impact None

Availability Impact High

User Interaction None

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

The EPSS score is 0.0004.

Exploitation none

Automatable yes

Technical Impact partial

Affected Vendors & Products

Vendors Products
Juniper Networks Subscribe
Junos Os Subscribe

No data.

No data.

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Vendors Products
Juniper Networks Subscribe
Junos Os Subscribe
Advisories

No advisories yet.

Fixes

Solution

The following software releases have been updated to resolve this specific issue: 23.4R2-S5, 24.2R2-S1, 24.4R2, 24.4R2-S1, 25.2R1, and all subsequent releases.

Workaround

There are no known workarounds for this issue.

References
Link Providers
https://kb.juniper.net/JSA106020 cve-icon cve-icon
https://supportportal.juniper.net/JSA106020 cve-icon cve-icon
History

Fri, 16 Jan 2026 14:15:00 +0000

Type Values Removed Values Added
First Time appeared Juniper Networks
Juniper Networks junos Os
Vendors & Products Juniper Networks
Juniper Networks junos Os

Thu, 15 Jan 2026 21:15:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Thu, 15 Jan 2026 20:45:00 +0000

Type Values Removed Values Added
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). 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. This issue affects Junos OS on SRX Series: * 23.4 versions before 23.4R2-S5, * 24.2 versions before 24.2R2-S1, * 24.4 versions before 24.4R2. This issue does not affect Junos OS versions before 23.4R1.
Title Junos OS: SRX Series: If a specific request is processed by the DNS subsystem flowd will crash
Weaknesses CWE-252
References
Metrics cvssV3_1

{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'}

cvssV4_0

{'score': 8.7, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:L/AU:Y/R:A/RE:M'}

Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: juniper

Published:

Updated: 2026-01-15T20:59:21.070Z

Reserved: 2026-01-05T17:32:48.712Z

Link: CVE-2026-21920

cve-icon Vulnrichment

Updated: 2026-01-15T20:59:08.031Z

cve-icon NVD

Status : Awaiting Analysis

Published: 2026-01-15T21:16:08.217

Modified: 2026-01-16T15:55:12.257

Link: CVE-2026-21920

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-01-16T13:42:57Z

Weaknesses