CVE-2026-21920 — Junos OS: SRX Series: If a specific request is processed by the DNS subsystem flowd will crash

Description (CNA)

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.

Affected (CNA)

Vendor / product	Versions
Juniper Networks / Junos OS	affected 23.4 before 23.4R2-S5; affected 24.2 before 24.2R2-S1; affected 24.4 before 24.4R2; unaffected 0 before 23.4R1

CWE

CWE-252

References

https://supportportal.juniper.net/JSA106020
https://kb.juniper.net/JSA106020

ADP enrichment

CISA-ADP

No English description supplied.

No references supplied.