High [CVE-2026-21920] Unchecked Return Value vulnerability in the DNS module of Juniper Networks Junos OS on SRX Series
This high-severity Juniper Networks advisory covers CVE-2026-21920 affecting Junos, Junos OS, SRX.
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Summary
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,
This issue does not affect Junos OS versions before 23.4R1.
- 23.4
- 24.2
- 24.4
Official advisory · high-confidence parse· fetched 2 months ago·verify at source
- 23.4R2-S5
- 24.2R2-S1
- 24.4R2
- 23.4R1
Official advisory · high-confidence parse· fetched 2 months ago·verify at source
Mitigation
Upgrade to a fixed release: 23.4R2-S5, 24.2R2-S1, 24.4R2, 23.4R1. That is the remediation for this advisory.
The vendor advisory may list additional interim mitigations or workarounds not captured here — review it before change work.
Official advisory · high-confidence parse· fetched 2 months ago·verify at source
Discussion(0)
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