CVE-2026-21920

highpriority · track · 0EPSS 0.005 · 41 %ileDEEUNLUS

grimoire priorityP2 · Scheduled

Exploitable?

—

no known exploitation

Likely / severe?

0.48% (41st) EPSS

CVSS 7.5 · high

Is it mine?

12 products

Check your exposure

Who says so?

5 sources

cnnvd · enisa_euvd · cert_bund · ncsc_nl

EPSS · scored 2026-10-27

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.

cvss

Technical severity, 0–10. One row per scoring source.

8.7

010

base score 0–10 · higher = more severe · hover a vector to decode⚠ sources disagree · medium–high · 6.6–8.7

v3.17.5highCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:Hsecondary · sirt@juniper.net USexploitability 3.9 · impact 3.6

v3.17.5highCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:Hsecondary · NCSC-NL NL

v4.08.7highCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:L/AU:Y/R:A/RE:Msecondary · ENISA EU

v4.08.7highCVSS: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:Xsecondary · sirt@juniper.net US

v4.06.6mediumCVSS: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:U/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:Xsecondary · CVSS-BT (t0sche)

ssvc

A stakeholder decision — act, attend, or track — from exploitation and impact.

Exploitation: none · Automatable: yes · Technical Impact: partialcoordinatorcisa_ssvcUS

weaknesses

The CWE weakness classes this flaw belongs to.

CWE-252USCWE-252US

affected products (12)

Products and version ranges known to be affected.

Juniper JUNOS OS SRX Seriesall versionscert_bundDEcpe:/o:juniper:junos:os_srx_series
Juniper Networks Junos OS23.4 → 23.4R2-S5enisa_euvdEU
Juniper Networks Junos OS24.2 → 24.2R2-S1enisa_euvdEU
Juniper Networks Junos OS24.4 → 24.4R2enisa_euvdEU
Juniper Networks Junos OS≤ vers:unknown/*ncsc_nlNL
Juniper Networks Junos OS Evolved≤ vers:unknown/*ncsc_nlNL
Juniper Networks Junos Space≤ vers:unknown/*ncsc_nlNL
Juniper Networks Paragon Automation (Pathfinder, Planner, Insights)≤ vers:unknown/*ncsc_nlNL
Juniper Networks Spac≤ vers:unknown/*ncsc_nlNL
juniper junos= 23.4nvdUScpe:2.3:o:juniper:junos:*:*:*:*:*:*:*:*
juniper junos= 24.2nvdUScpe:2.3:o:juniper:junos:*:*:*:*:*:*:*:*
juniper junos= 24.4nvdUScpe:2.3:o:juniper:junos:*:*:*:*:*:*:*:*

advisories (2)

Vendor and ecosystem advisories describing this.

NCSC-2026-0017Kwetsbaarheden verholpen in Juniper Networks JunOSNL2026-01-16csaf · ncsc_nlNL
Juniper heeft kwetsbaarheden verholpen in Junos OS (Specifiek voor SRX en MX Series apparaten).
WID-SEC-W-2026-0117Juniper Junos OS, Junos Space: Mehrere SchwachstellenDeutsch2026-01-14csaf · cert_bundDE
Ein Angreifer kann mehrere Schwachstellen in Juniper JUNOS und Juniper Junos Space ausnutzen, um falsche Informationen darzustellen, beliebigen Code mit Root-Rechten auszuführen, Daten zu manipulieren, vertrauliche Informationen offenzulegen und einen Denial-of-Service-Zustand zu verursachen.

also known as (3)

Other names and identifiers for this entity.

sources

Which sources assert this record, and when.

cnnvd enisa_euvd cert_bund ncsc_nl nvd NVD CVE.org MITRE

published 2026-01-15modified 2026-06-17

references (7)

External citations — patches, advisories, analysis.

scry

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