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CVE-2026-21920

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CVE-2026-21920

Published: Jan 15, 2026

Modified: Jan 15, 2026

PUBLISHED

CVSS v3.1

7.5

HIGH

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.

VendorProductVersions

Juniper Networks

Junos OS

affected
23.4 - < 23.4R2-S5
affected
24.2 - < 24.2R2-S1
affected
24.4 - < 24.4R2
unaffected
0 - < 23.4R1

Weaknesses (CWE)

CWE-252

CVSS v3.1 Details

CVSS v3.1 Vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

None

Availability

High

References

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