CVE-2026-21919

{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-21919", "assignerOrgId": "8cbe9d5a-a066-4c94-8978-4b15efeae968", "state": "PUBLISHED", "assignerShortName": "juniper", "dateReserved": "2026-01-05T17:32:48.711Z", "datePublished": "2026-04-09T21:26:46.081Z", "dateUpdated": "2026-04-13T18:06:20.368Z"}, "containers": {"cna": {"affected": [{"defaultStatus": "unaffected", "product": "Junos OS", "vendor": "Juniper Networks", "versions": [{"lessThan": "23.4R2-S4", "status": "affected", "version": "23.4", "versionType": "semver"}, {"lessThan": "24.2R2-S1", "status": "affected", "version": "24.2", "versionType": "semver"}, {"lessThan": "24.4R1-S3, 24.4R2", "status": "affected", "version": "24.4", "versionType": "semver"}, {"lessThan": "23.4R1", "status": "unaffected", "version": "all version prior to", "versionType": "semver"}]}, {"defaultStatus": "unaffected", "product": "Junos OS Evolved", "vendor": "Juniper Networks", "versions": [{"lessThan": "23.4R2-S5-EVO", "status": "affected", "version": "23.4", "versionType": "semver"}, {"lessThan": "24.2R2-S1-EVO", "status": "affected", "version": "24.2", "versionType": "semver"}, {"lessThan": "24.4R1-S3-EVO, 24.4R2-EVO", "status": "affected", "version": "24.4", "versionType": "semver"}, {"lessThan": "23.4R1-EVO", "status": "unaffected", "version": "all version prior to", "versionType": "semver"}]}], "configurations": [{"lang": "en", "supportingMedia": [{"base64": false, "type": "text/html", "value": "To be exposed to this issue the device needs to be configured for NETCONF as follows:<br><br><tt>[ system services&nbsp;netconf ... ]</tt>"}], "value": "To be exposed to this issue the device needs to be configured for NETCONF as follows:\n\n[ system services\u00a0netconf ... ]"}], "datePublic": "2026-04-08T16:00:00.000Z", "descriptions": [{"lang": "en", "supportingMedia": [{"base64": false, "type": "text/html", "value": "An Incorrect Synchronization vulnerability in the management daemon (mgd) of Juniper Networks Junos OS and Junos OS Evolved allows a network-based attacker with low privileges to cause a complete Denial-of-Service (DoS) of the management plane.<br><br>When NETCONF sessions are quickly established and disconnected, a locking issue causes mgd processes to hang in an unusable state. When the maximum number of mgd processes has been reached, no new logins are possible. This leads to the inability to manage the device and requires a power-cycle to recover.<br><br>This issue can be monitored by checking for mgd processes in lockf state in the output of 'show system processes extensive':<br><br><tt>user@host&gt; show system processes extensive | match mgd<br>&lt;pid&gt; root &nbsp; &nbsp; &nbsp; 20 &nbsp; 0 501M 4640K lockf &nbsp; 1 0:01 0.00% mgd</tt><p><br></p><p>If the system still can be accessed (either via the CLI or as root, which might still be possible as last resort as this won't invoke mgd), mgd processes in this state can be killed with 'request system process terminate &lt;PID&gt;' from the CLI or with 'kill -9 &lt;PID&gt;' from the shell.&nbsp;</p><p><br></p><p>This issue affects:</p><p>Junos OS:</p><ul><li>23.4 versions before 23.4R2-S4,</li><li>24.2 versions before 24.2R2-S1,</li><li>24.4 versions before 24.4R1-S3, 24.4R2;</li></ul>\n\n<p>This issue does not affect Junos OS versions before 23.4R1;</p>\n\n<p>Junos OS Evolved:</p><ul><li>23.4 versions before 23.4R2-S5-EVO,</li><li>24.2 versions before 24.2R2-S1-EVO,</li><li>24.4 versions before 24.4R1-S3-EVO, 24.4R2-EVO.</li></ul><p>\n\n</p><p>This issue does not affect Junos OS Evolved versions before 23.4R1-EVO;</p>\n\n\n\n<br>"}], "value": "An Incorrect Synchronization vulnerability in the management daemon (mgd) of Juniper Networks Junos OS and Junos OS Evolved allows a network-based attacker with low privileges to cause a complete Denial-of-Service (DoS) of the management plane.\n\nWhen NETCONF sessions are quickly established and disconnected, a locking issue causes mgd processes to hang in an unusable state. When the maximum number of mgd processes has been reached, no new logins are possible. This leads to the inability to manage the device and requires a power-cycle to recover.\n\nThis issue can be monitored by checking for mgd processes in lockf state in the output of 'show system processes extensive':\n\nuser@host> show system processes extensive | match mgd\n<pid> root \u00a0 \u00a0 \u00a0 20 \u00a0 0 501M 4640K lockf \u00a0 1 0:01 0.00% mgd\n\n\nIf the system still can be accessed (either via the CLI or as root, which might still be possible as last resort as this won't invoke mgd), mgd processes in this state can be killed with 'request system process terminate <PID>' from the CLI or with 'kill -9 <PID>' from the shell.\u00a0\n\n\n\n\nThis issue affects:\n\nJunos OS:\n\n * 23.4 versions before 23.4R2-S4,\n * 24.2 versions before 24.2R2-S1,\n * 24.4 versions before 24.4R1-S3, 24.4R2;\n\n\n\n\nThis issue does not affect Junos OS versions before 23.4R1;\n\n\n\nJunos OS Evolved:\n\n * 23.4 versions before 23.4R2-S5-EVO,\n * 24.2 versions before 24.2R2-S1-EVO,\n * 24.4 versions before 24.4R1-S3-EVO, 24.4R2-EVO.\n\n\n\n\n\n\nThis issue does not affect Junos OS Evolved versions before 23.4R1-EVO;"}], "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": 6.5, "baseSeverity": "MEDIUM", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "privilegesRequired": "LOW", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/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": "USER", "Safety": "NOT_DEFINED", "attackComplexity": "LOW", "attackRequirements": "NONE", "attackVector": "NETWORK", "baseScore": 7.1, "baseSeverity": "HIGH", "privilegesRequired": "LOW", "providerUrgency": "NOT_DEFINED", "subAvailabilityImpact": "NONE", "subConfidentialityImpact": "NONE", "subIntegrityImpact": "NONE", "userInteraction": "NONE", "valueDensity": "NOT_DEFINED", "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/AU:Y/R:U/RE:M", "version": "4.0", "vulnAvailabilityImpact": "HIGH", "vulnConfidentialityImpact": "NONE", "vulnIntegrityImpact": "NONE", "vulnerabilityResponseEffort": "MODERATE"}, "format": "CVSS", "scenarios": [{"lang": "en", "value": "GENERAL"}]}], "problemTypes": [{"descriptions": [{"cweId": "CWE-821", "description": "CWE-821 Incorrect Synchronization", "lang": "en", "type": "CWE"}]}], "providerMetadata": {"orgId": "8cbe9d5a-a066-4c94-8978-4b15efeae968", "shortName": "juniper", "dateUpdated": "2026-04-09T21:26:46.081Z"}, "references": [{"tags": ["vendor-advisory"], "url": "https://kb.juniper.net/JSA106019"}], "solutions": [{"lang": "en", "supportingMedia": [{"base64": false, "type": "text/html", "value": "The following software releases have been updated to resolve this specific issue:<br>Junos OS Evolved: 23.4R2-S5-EVO, 24.2R2-S1-EVO, 24.4R1-S3-EVO, 24.4R2-EVO, 25.2R1-EVO,&nbsp;and all subsequent releases;<br>Junos OS: 23.4R2-S4, 24.2R2-S1, 24.4R1-S3, 24.4R2, 25.2R1, and all subsequent releases."}], "value": "The following software releases have been updated to resolve this specific issue:\nJunos OS Evolved: 23.4R2-S5-EVO, 24.2R2-S1-EVO, 24.4R1-S3-EVO, 24.4R2-EVO, 25.2R1-EVO,\u00a0and all subsequent releases;\nJunos OS: 23.4R2-S4, 24.2R2-S1, 24.4R1-S3, 24.4R2, 25.2R1, and all subsequent releases."}], "source": {"advisory": "JSA106019", "defect": ["1866577"], "discovery": "INTERNAL"}, "title": "Junos OS and Junos OS Evolved: A high frequency of connecting and disconnecting NETCONF sessions causes management unavailability", "workarounds": [{"lang": "en", "supportingMedia": [{"base64": false, "type": "text/html", "value": "Use access lists or firewall filters to limit access to the device only from trusted hosts and administrators.<br><br>To further reduce the risk of exploitation you can set values as low as needed for your normal operations for:<br><br><tt>[ system services netconf&nbsp;ssh&nbsp;connection-limit &lt;max_connections&gt; ]<br>[ system services netconf ssh&nbsp;rate-limit &lt;connections_per_minute&gt; ]</tt><br>"}], "value": "Use access lists or firewall filters to limit access to the device only from trusted hosts and administrators.\n\nTo further reduce the risk of exploitation you can set values as low as needed for your normal operations for:\n\n[ system services netconf\u00a0ssh\u00a0connection-limit <max_connections> ]\n[ system services netconf ssh\u00a0rate-limit <connections_per_minute> ]"}], "x_generator": {"engine": "Vulnogram 0.1.0-dev"}}, "adp": [{"metrics": [{"other": {"type": "ssvc", "content": {"id": "CVE-2026-21919", "role": "CISA Coordinator", "options": [{"Exploitation": "none"}, {"Automatable": "no"}, {"Technical Impact": "partial"}], "version": "2.0.3", "timestamp": "2026-04-13T17:38:59.428723Z"}}}], "title": "CISA ADP Vulnrichment", "providerMetadata": {"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-04-13T18:06:20.368Z"}}]}}

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]<br>[ system services netconf ssh&nbsp;rate-limit &lt;connections_per_minute&gt; ]</tt><br>", "base64": false}]}], "x_generator": {"engine": "Vulnogram 0.1.0-dev"}, "descriptions": [{"lang": "en", "value": "An Incorrect Synchronization vulnerability in the management daemon (mgd) of Juniper Networks Junos OS and Junos OS Evolved allows a network-based attacker with low privileges to cause a complete Denial-of-Service (DoS) of the management plane.\n\nWhen NETCONF sessions are quickly established and disconnected, a locking issue causes mgd processes to hang in an unusable state. When the maximum number of mgd processes has been reached, no new logins are possible. This leads to the inability to manage the device and requires a power-cycle to recover.\n\nThis issue can be monitored by checking for mgd processes in lockf state in the output of 'show system processes extensive':\n\nuser@host> show system processes extensive | match mgd\n<pid> root \u00a0 \u00a0 \u00a0 20 \u00a0 0 501M 4640K lockf \u00a0 1 0:01 0.00% mgd\n\n\nIf the system still can be accessed (either via the CLI or as root, which might still be possible as last resort as this won't invoke mgd), mgd processes in this state can be killed with 'request system process terminate <PID>' from the CLI or with 'kill -9 <PID>' from the shell.\u00a0\n\n\n\n\nThis issue affects:\n\nJunos OS:\n\n * 23.4 versions before 23.4R2-S4,\n * 24.2 versions before 24.2R2-S1,\n * 24.4 versions before 24.4R1-S3, 24.4R2;\n\n\n\n\nThis issue does not affect Junos OS versions before 23.4R1;\n\n\n\nJunos OS Evolved:\n\n * 23.4 versions before 23.4R2-S5-EVO,\n * 24.2 versions before 24.2R2-S1-EVO,\n * 24.4 versions before 24.4R1-S3-EVO, 24.4R2-EVO.\n\n\n\n\n\n\nThis issue does not affect Junos OS Evolved versions before 23.4R1-EVO;", "supportingMedia": [{"type": "text/html", "value": "An Incorrect Synchronization vulnerability in the management daemon (mgd) of Juniper Networks Junos OS and Junos OS Evolved allows a network-based attacker with low privileges to cause a complete Denial-of-Service (DoS) of the management plane.<br><br>When NETCONF sessions are quickly established and disconnected, a locking issue causes mgd processes to hang in an unusable state. When the maximum number of mgd processes has been reached, no new logins are possible. This leads to the inability to manage the device and requires a power-cycle to recover.<br><br>This issue can be monitored by checking for mgd processes in lockf state in the output of 'show system processes extensive':<br><br><tt>user@host&gt; show system processes extensive | match mgd<br>&lt;pid&gt; root &nbsp; &nbsp; &nbsp; 20 &nbsp; 0 501M 4640K lockf &nbsp; 1 0:01 0.00% mgd</tt><p><br></p><p>If the system still can be accessed (either via the CLI or as root, which might still be possible as last resort as this won't invoke mgd), mgd processes in this state can be killed with 'request system process terminate &lt;PID&gt;' from the CLI or with 'kill -9 &lt;PID&gt;' from the shell.&nbsp;</p><p><br></p><p>This issue affects:</p><p>Junos OS:</p><ul><li>23.4 versions before 23.4R2-S4,</li><li>24.2 versions before 24.2R2-S1,</li><li>24.4 versions before 24.4R1-S3, 24.4R2;</li></ul>\n\n<p>This issue does not affect Junos OS versions before 23.4R1;</p>\n\n<p>Junos OS Evolved:</p><ul><li>23.4 versions before 23.4R2-S5-EVO,</li><li>24.2 versions before 24.2R2-S1-EVO,</li><li>24.4 versions before 24.4R1-S3-EVO, 24.4R2-EVO.</li></ul><p>\n\n</p><p>This issue does not affect Junos OS Evolved versions before 23.4R1-EVO;</p>\n\n\n\n<br>", "base64": false}]}], "problemTypes": [{"descriptions": [{"lang": "en", "type": "CWE", "cweId": "CWE-821", "description": "CWE-821 Incorrect Synchronization"}]}], "configurations": [{"lang": "en", "value": "To be exposed to this issue the device needs to be configured for NETCONF as follows:\n\n[ system services\u00a0netconf ... ]", "supportingMedia": [{"type": "text/html", "value": "To be exposed to this issue the device needs to be configured for NETCONF as follows:<br><br><tt>[ system services&nbsp;netconf ... ]</tt>", "base64": false}]}], "providerMetadata": {"orgId": "8cbe9d5a-a066-4c94-8978-4b15efeae968", "shortName": "juniper", "dateUpdated": "2026-04-09T21:26:46.081Z"}}}, "cveMetadata": {"cveId": "CVE-2026-21919", "state": "PUBLISHED", "dateUpdated": "2026-04-13T18:06:20.368Z", "dateReserved": "2026-01-05T17:32:48.711Z", "assignerOrgId": "8cbe9d5a-a066-4c94-8978-4b15efeae968", "datePublished": "2026-04-09T21:26:46.081Z", "assignerShortName": "juniper"}, "dataVersion": "5.2"}

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When the maximum number of mgd processes has been reached, no new logins are possible. This leads to the inability to manage the device and requires a power-cycle to recover.\n\nThis issue can be monitored by checking for mgd processes in lockf state in the output of 'show system processes extensive':\n\nuser@host> show system processes extensive | match mgd\n<pid> root \u00a0 \u00a0 \u00a0 20 \u00a0 0 501M 4640K lockf \u00a0 1 0:01 0.00% mgd\n\n\nIf the system still can be accessed (either via the CLI or as root, which might still be possible as last resort as this won't invoke mgd), mgd processes in this state can be killed with 'request system process terminate <PID>' from the CLI or with 'kill -9 <PID>' from the shell.\u00a0\n\n\n\n\nThis issue affects:\n\nJunos OS:\n\n * 23.4 versions before 23.4R2-S4,\n * 24.2 versions before 24.2R2-S1,\n * 24.4 versions before 24.4R1-S3, 24.4R2;\n\n\n\n\nThis issue does not affect Junos OS versions before 23.4R1;\n\n\n\nJunos OS Evolved:\n\n * 23.4 versions before 23.4R2-S5-EVO,\n * 24.2 versions before 24.2R2-S1-EVO,\n * 24.4 versions before 24.4R1-S3-EVO, 24.4R2-EVO.\n\n\n\n\n\n\nThis issue does not affect Junos OS Evolved versions before 23.4R1-EVO;"}, {"lang": "es", "value": "Una vulnerabilidad de sincronizaci\u00f3n incorrecta en el demonio de gesti\u00f3n (mgd) de Juniper Networks Junos OS y Junos OS Evolved permite a un atacante basado en red con privilegios bajos causar una denegaci\u00f3n de servicio (DoS) completa del plano de gesti\u00f3n.\n\nCuando las sesiones NETCONF se establecen y desconectan r\u00e1pidamente, un problema de bloqueo hace que los procesos mgd se cuelguen en un estado inutilizable. Cuando se ha alcanzado el n\u00famero m\u00e1ximo de procesos mgd, no es posible iniciar nuevas sesiones. Esto lleva a la incapacidad de gestionar el dispositivo y requiere un ciclo de encendido para recuperarse.\n\nEste problema se puede monitorear buscando procesos mgd en estado lockf en la salida de \u2019show system processes extensive\u2019:\n\nuser@host> show system processes extensive | match mgd\n[pid] root 20 0 501M 4640K lockf 1 0:01 0.00% mgd\n\nSi a\u00fan se puede acceder al sistema (ya sea a trav\u00e9s de la CLI o como root, lo que a\u00fan podr\u00eda ser posible como \u00faltimo recurso ya que esto no invocar\u00e1 mgd), los procesos mgd en este estado pueden terminarse con \u2019request system process terminate [PID]\u2019 desde la CLI o con \u2019kill -9 [PID]\u2019 desde la shell.\n\nEste problema afecta:\n\nJunos OS:\n\n * versiones 23.4 anteriores a 23.4R2-S4,\n * versiones 24.2 anteriores a 24.2R2-S1,\n * versiones 24.4 anteriores a 24.4R1-S3, 24.4R2;\n\nEste problema no afecta a las versiones de Junos OS anteriores a 23.4R1;\n\nJunos OS Evolved:\n\n * versiones 23.4 anteriores a 23.4R2-S5-EVO,\n * versiones 24.2 anteriores a 24.2R2-S1-EVO,\n * versiones 24.4 anteriores a 24.4R1-S3-EVO, 24.4R2-EVO.\n\nEste problema no afecta a las versiones de Junos OS Evolved anteriores a 23.4R1-EVO;"}], "id": "CVE-2026-21919", "lastModified": "2026-10-26T21:10:00.170", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "HIGH", "baseScore": 6.5, "baseSeverity": "MEDIUM", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "privilegesRequired": "LOW", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H", "version": "3.1"}, "exploitabilityScore": 2.8, "impactScore": 3.6, "source": "sirt@juniper.net", "type": "Secondary"}], "cvssMetricV40": [{"cvssData": {"Automatable": "YES", "Recovery": "USER", "Safety": "NOT_DEFINED", "attackComplexity": "LOW", "attackRequirements": "NONE", "attackVector": "NETWORK", "availabilityRequirement": "NOT_DEFINED", "baseScore": 7.1, "baseSeverity": "HIGH", "confidentialityRequirement": "NOT_DEFINED", "exploitMaturity": "NOT_DEFINED", "integrityRequirement": "NOT_DEFINED", "modifiedAttackComplexity": "NOT_DEFINED", "modifiedAttackRequirements": "NOT_DEFINED", "modifiedAttackVector": "NOT_DEFINED", "modifiedPrivilegesRequired": "NOT_DEFINED", "modifiedSubAvailabilityImpact": "NOT_DEFINED", "modifiedSubConfidentialityImpact": "NOT_DEFINED", "modifiedSubIntegrityImpact": "NOT_DEFINED", "modifiedUserInteraction": "NOT_DEFINED", "modifiedVulnAvailabilityImpact": "NOT_DEFINED", "modifiedVulnConfidentialityImpact": "NOT_DEFINED", "modifiedVulnIntegrityImpact": "NOT_DEFINED", "privilegesRequired": "LOW", "providerUrgency": "NOT_DEFINED", "subAvailabilityImpact": "NONE", "subConfidentialityImpact": "NONE", "subIntegrityImpact": "NONE", "userInteraction": "NONE", "valueDensity": "NOT_DEFINED", "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/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:U/V:X/RE:M/U:X", "version": "4.0", "vulnAvailabilityImpact": "HIGH", "vulnConfidentialityImpact": "NONE", "vulnIntegrityImpact": "NONE", "vulnerabilityResponseEffort": "MODERATE"}, "source": "sirt@juniper.net", "type": "Secondary"}], "ssvcV203": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": {"id": "CVE-2026-21919", "options": [{"exploitation": "none"}, {"automatable": "no"}, {"technicalImpact": "partial"}], "role": "CISA Coordinator", "timestamp": "2026-04-13T17:38:59.428723Z", "version": "2.0.3"}}]}, "published": "2026-04-09T22:16:25.173", "references": [{"source": "sirt@juniper.net", "tags": ["Mitigation", "Vendor Advisory"], "url": "https://kb.juniper.net/JSA106019"}], "sourceIdentifier": "sirt@juniper.net", "vulnStatus": "Analyzed", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-821"}], "source": "sirt@juniper.net", "type": "Secondary"}]}

{}

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