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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.

PUBLISHED Reserved 2026-01-05 | Published 2026-01-15 | Updated 2026-01-15 | Assigner juniper




HIGH: 7.5CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

HIGH: 8.7CVSS: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

Problem types

CWE-252 Unchecked Return Value

Product status

Default status
unaffected

23.4 (semver) before 23.4R2-S5
affected

24.2 (semver) before 24.2R2-S1
affected

24.4 (semver) before 24.4R2
affected

Any version before 23.4R1
unaffected

References

supportportal.juniper.net/JSA106020 vendor-advisory

kb.juniper.net/JSA106020 vendor-advisory

cve.org (CVE-2026-21920)

nvd.nist.gov (CVE-2026-21920)

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