CVE-2026-21920
published 2026-01-15CVE-2026-21920: 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…
PriorityP348high7.5CVSS 3.1
AVNACLPRNUINSUCNINAH
EPSS
0.44%
35.5th percentile
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
8 ranges
| Vendor | Product | Version range | Fixed in |
|---|---|---|---|
| juniper | junos | — | — |
| juniper | junos | — | — |
| juniper | junos | — | — |
| juniper | junos_os | — | — |
| juniper | srx_series | — | — |
| juniper_networks | junos_os | >= 23.4 < 23.4R2-S5 | 23.4R2-S5 |
| juniper_networks | junos_os | >= 24.2 < 24.2R2-S1 | 24.2R2-S1 |
| juniper_networks | junos_os | >= 24.4 < 24.4R2 | 24.4R2 |
CVSS provenance
nvdv3.17.5HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
nvdv4.08.7HIGHCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:L/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:Y/R:A/V:X/RE:M/U:X
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Juniper
CVE-2026-21920: An Unchecked Return Value vulnerability in the DNS module of Juniper Networks Junos OS on SRX Series allows an unauthenticated, network-based attacker
vendor_juniper·2026-01-15·CVSS 7.5
CVE-2026-21920 [HIGH] CWE-252 CVE-2026-21920: An Unchecked Return Value vulnerability in the DNS module of Juniper Networks Junos OS on SRX Series allows an unauthenticated, network-based attacker
CVE-2026-21920: 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.
GHSA
GHSA-vj9c-h3r9-jwrf: An Unchecked Return Value vulnerability in the DNS module of Juniper Networks Junos OS on SRX Series allows an unauthenticated, network-based attacker
ghsa_unreviewed·2026-01-15
CVE-2026-21920 [HIGH] CWE-252 GHSA-vj9c-h3r9-jwrf: An Unchecked Return Value vulnerability in the DNS module of Juniper Networks Junos OS on SRX Series allows an unauthenticated, network-based attacker
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.
No detection rules found.
No public exploits indexed.
No writeups or analysis indexed.
2026-01-15
Published