What is CVE-2026-21920?

CVE-2026-21920 is a high-severity vulnerability in Juniper Junos, classified under CWE-252. CVSS score: 7.5/10. Published 2026-01-15.

How severe is CVE-2026-21920?

High severity. CVSS v3 base score is 7.5 out of 10.

Vulnerability in Juniper Junos

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 proce…

EPSS: 0.004 (34.8th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.

Affected products

Juniper Junos — versions 23.4, 24.2, 24.4
Juniper Srx1500
Juniper Srx1600
Juniper Srx2300
Juniper Srx300
Juniper Srx320
Juniper Srx340
Juniper Srx345
Juniper Srx380
Juniper Srx4100

Weakness classification (CWE)

CWE-252

References

sirt@juniper.net (vendor-advisory, Vendor Advisory)
sirt@juniper.net (vendor-advisory, Vendor Advisory)

Frequently asked questions

What is CVE-2026-21920?: CVE-2026-21920 is a high-severity vulnerability in Juniper Junos, classified under CWE-252. CVSS score: 7.5/10. Published 2026-01-15.
How severe is CVE-2026-21920?: High severity. CVSS v3 base score is 7.5 out of 10.