{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-21920","assignerOrgId":"8cbe9d5a-a066-4c94-8978-4b15efeae968","state":"PUBLISHED","assignerShortName":"juniper","dateReserved":"2026-01-05T17:32:48.712Z","datePublished":"2026-01-15T20:28:10.526Z","dateUpdated":"2026-01-15T20:59:21.070Z"},"containers":{"cna":{"affected":[{"defaultStatus":"unaffected","platforms":["SRX Series"],"product":"Junos OS","vendor":"Juniper Networks","versions":[{"lessThan":"23.4R2-S5","status":"affected","version":"23.4","versionType":"semver"},{"lessThan":"24.2R2-S1","status":"affected","version":"24.2","versionType":"semver"},{"lessThan":"24.4R2","status":"affected","version":"24.4","versionType":"semver"},{"lessThan":"23.4R1","status":"unaffected","version":"0","versionType":"semver"}]}],"configurations":[{"lang":"en","supportingMedia":[{"base64":false,"type":"text/html","value":"A device is exposed to this issue when one of the following features are used / configurations are present:

- GeoIP:

[ security dynamic-address address-name <name> profile category GeoIP ... ]


- DNS security:

[ services security-metadata-streaming policy <name> dns detections ... ]

or

[ services security-intelligence profile <profile-name> category DNS ]
[ services security-intelligence profile policy <policy-name> DNS <profile-name> ]

\n\n"}],"value":"A device is exposed to this issue when one of the following features are used / configurations are present:\n\n- GeoIP:\n\n[ security dynamic-address address-name profile category GeoIP ... ]\n\n\n- DNS security:\n\n[ services security-metadata-streaming policy dns detections ... ]\n\nor\n\n[ services security-intelligence profile category DNS ]\n[ services security-intelligence profile policy DNS ]"}],"datePublic":"2026-01-14T17:00:00.000Z","descriptions":[{"lang":"en","supportingMedia":[{"base64":false,"type":"text/html","value":"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).
\n\n

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.

\n\n

This issue does not affect Junos OS versions before 23.4R1.

"}],"value":"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).\n\n\n\n\nIf 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.\n\nThis issue affects Junos OS on SRX Series:\n\n\n\n * 23.4 versions before 23.4R2-S5,\n * 24.2 versions before 24.2R2-S1,\n * 24.4 versions before 24.4R2.\n\n\n\n\n\n\nThis issue does not affect Junos OS versions before 23.4R1."}],"exploits":[{"lang":"en","supportingMedia":[{"base64":false,"type":"text/html","value":"Juniper SIRT is not aware of any malicious exploitation of this vulnerability."}],"value":"Juniper SIRT is not aware of any malicious exploitation of this vulnerability."}],"metrics":[{"cvssV3_1":{"attackComplexity":"LOW","attackVector":"NETWORK","availabilityImpact":"HIGH","baseScore":7.5,"baseSeverity":"HIGH","confidentialityImpact":"NONE","integrityImpact":"NONE","privilegesRequired":"NONE","scope":"UNCHANGED","userInteraction":"NONE","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","version":"3.1"},"format":"CVSS","scenarios":[{"lang":"en","value":"GENERAL"}]},{"cvssV4_0":{"Automatable":"YES","Recovery":"AUTOMATIC","Safety":"NOT_DEFINED","attackComplexity":"LOW","attackRequirements":"NONE","attackVector":"NETWORK","baseScore":8.7,"baseSeverity":"HIGH","privilegesRequired":"NONE","providerUrgency":"NOT_DEFINED","subAvailabilityImpact":"LOW","subConfidentialityImpact":"NONE","subIntegrityImpact":"NONE","userInteraction":"NONE","valueDensity":"NOT_DEFINED","vectorString":"CVSS: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","version":"4.0","vulnAvailabilityImpact":"HIGH","vulnConfidentialityImpact":"NONE","vulnIntegrityImpact":"NONE","vulnerabilityResponseEffort":"MODERATE"},"format":"CVSS","scenarios":[{"lang":"en","value":"GENERAL"}]}],"problemTypes":[{"descriptions":[{"cweId":"CWE-252","description":"CWE-252 Unchecked Return Value","lang":"en","type":"CWE"}]}],"providerMetadata":{"orgId":"8cbe9d5a-a066-4c94-8978-4b15efeae968","shortName":"juniper","dateUpdated":"2026-01-15T20:28:10.526Z"},"references":[{"tags":["vendor-advisory"],"url":"https://supportportal.juniper.net/JSA106020"},{"tags":["vendor-advisory"],"url":"https://kb.juniper.net/JSA106020"}],"solutions":[{"lang":"en","supportingMedia":[{"base64":false,"type":"text/html","value":"The following software releases have been updated to resolve this specific issue: 23.4R2-S5, 24.2R2-S1, 24.4R2, 24.4R2-S1, 25.2R1, and all subsequent releases."}],"value":"The following software releases have been updated to resolve this specific issue: 23.4R2-S5, 24.2R2-S1, 24.4R2, 24.4R2-S1, 25.2R1, and all subsequent releases."}],"source":{"advisory":"JSA106020","defect":["1851909"],"discovery":"USER"},"title":"Junos OS: SRX Series: If a specific request is processed by the DNS subsystem flowd will crash","workarounds":[{"lang":"en","supportingMedia":[{"base64":false,"type":"text/html","value":"There are no known workarounds for this issue."}],"value":"There are no known workarounds for this issue."}],"x_generator":{"engine":"Vulnogram 0.1.0-dev"}},"adp":[{"metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-01-15T20:58:50.543674Z","id":"CVE-2026-21920","options":[{"Exploitation":"none"},{"Automatable":"yes"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"title":"CISA ADP Vulnrichment","providerMetadata":{"orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","shortName":"CISA-ADP","dateUpdated":"2026-01-15T20:59:21.070Z"}}]}}