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.
History

Fri, 23 Jan 2026 19:00:00 +0000

Type Values Removed Values Added
First Time appeared Juniper
Juniper junos
Juniper srx1500
Juniper srx1600
Juniper srx2300
Juniper srx300
Juniper srx320
Juniper srx340
Juniper srx345
Juniper srx380
Juniper srx4100
Juniper srx4120
Juniper srx4200
Juniper srx4300
Juniper srx4600
Juniper srx4700
Juniper srx5400
Juniper srx5600
Juniper srx5800
CPEs cpe:2.3:h:juniper:srx1500:-:*:*:*:*:*:*:*
cpe:2.3:h:juniper:srx1600:-:*:*:*:*:*:*:*
cpe:2.3:h:juniper:srx2300:-:*:*:*:*:*:*:*
cpe:2.3:h:juniper:srx300:-:*:*:*:*:*:*:*
cpe:2.3:h:juniper:srx320:-:*:*:*:*:*:*:*
cpe:2.3:h:juniper:srx340:-:*:*:*:*:*:*:*
cpe:2.3:h:juniper:srx345:-:*:*:*:*:*:*:*
cpe:2.3:h:juniper:srx380:-:*:*:*:*:*:*:*
cpe:2.3:h:juniper:srx4100:-:*:*:*:*:*:*:*
cpe:2.3:h:juniper:srx4120:-:*:*:*:*:*:*:*
cpe:2.3:h:juniper:srx4200:-:*:*:*:*:*:*:*
cpe:2.3:h:juniper:srx4300:-:*:*:*:*:*:*:*
cpe:2.3:h:juniper:srx4600:-:*:*:*:*:*:*:*
cpe:2.3:h:juniper:srx4700:-:*:*:*:*:*:*:*
cpe:2.3:h:juniper:srx5400:-:*:*:*:*:*:*:*
cpe:2.3:h:juniper:srx5600:-:*:*:*:*:*:*:*
cpe:2.3:h:juniper:srx5800:-:*:*:*:*:*:*:*
cpe:2.3:o:juniper:junos:23.4:-:*:*:*:*:*:*
cpe:2.3:o:juniper:junos:23.4:r1-s1:*:*:*:*:*:*
cpe:2.3:o:juniper:junos:23.4:r1-s2:*:*:*:*:*:*
cpe:2.3:o:juniper:junos:23.4:r1:*:*:*:*:*:*
cpe:2.3:o:juniper:junos:23.4:r2-s1:*:*:*:*:*:*
cpe:2.3:o:juniper:junos:23.4:r2-s2:*:*:*:*:*:*
cpe:2.3:o:juniper:junos:23.4:r2-s3:*:*:*:*:*:*
cpe:2.3:o:juniper:junos:23.4:r2-s4:*:*:*:*:*:*
cpe:2.3:o:juniper:junos:23.4:r2:*:*:*:*:*:*
cpe:2.3:o:juniper:junos:24.2:-:*:*:*:*:*:*
cpe:2.3:o:juniper:junos:24.2:r1-s1:*:*:*:*:*:*
cpe:2.3:o:juniper:junos:24.2:r1-s2:*:*:*:*:*:*
cpe:2.3:o:juniper:junos:24.2:r1:*:*:*:*:*:*
cpe:2.3:o:juniper:junos:24.2:r2:*:*:*:*:*:*
cpe:2.3:o:juniper:junos:24.4:-:*:*:*:*:*:*
cpe:2.3:o:juniper:junos:24.4:r1-s2:*:*:*:*:*:*
cpe:2.3:o:juniper:junos:24.4:r1-s3:*:*:*:*:*:*
cpe:2.3:o:juniper:junos:24.4:r1:*:*:*:*:*:*
Vendors & Products Juniper
Juniper junos
Juniper srx1500
Juniper srx1600
Juniper srx2300
Juniper srx300
Juniper srx320
Juniper srx340
Juniper srx345
Juniper srx380
Juniper srx4100
Juniper srx4120
Juniper srx4200
Juniper srx4300
Juniper srx4600
Juniper srx4700
Juniper srx5400
Juniper srx5600
Juniper srx5800

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'}


cve-icon MITRE

Status: PUBLISHED

Assigner: juniper

Published: 2026-01-15T20:28:10.526Z

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 : Analyzed

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

Modified: 2026-01-23T18:51:59.987

Link: CVE-2026-21920

cve-icon Redhat

No data.