{"id":"CVE-2025-21590","published":"2025-03-12T14:15:15Z","modified":"2026-10-01T18:23:34Z","title":"Juniper Junos OS Improper Isolation or Compartmentalization Vulnerability","vendor":"Juniper","product":"Junos OS","tier":"core","eol":null,"description":{"text":"An Improper Isolation or Compartmentalization vulnerability in the kernel of Juniper Networks Junos OS allows a local attacker with high privileges to compromise the integrity of the device.\n\nA local attacker with access to the shell is able to inject arbitrary code which can compromise an affected device.\nThis issue is not exploitable from the Junos CLI.\nThis issue affects Junos OS: \n\n\n\n  *  All versions before 21.2R3-S9,\n  *  21.4 versions before 21.4R3-S10, \n  *  22.2 versions before 22.2R3-S6, \n  *  22.4 versions before 22.4R3-S6, \n  *  23.2 versions before 23.2R2-S3, \n  *  23.4 versions before 23.4R2-S4,\n  *  24.2 versions before 24.2R1-S2, 24.2R2.","provenance":"source","from":"NVD"},"summary":{"text":"A flaw in the kernel of Juniper Networks Junos OS, an Improper Isolation or Compartmentalization issue, allows code injection that compromises the integrity of affected devices. An attacker needs local access to the device shell with high privileges, and the issue cannot be exploited from the Junos CLI.","provenance":"ai","model":"claude-haiku-5-5","generatedAt":"2026-10-23T07:14:28Z"},"cvss":{"score":4.4,"severity":"MEDIUM","version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:H/A:N","provenance":"source","from":"NVD"},"epss":{"score":0.01749,"percentile":0.77855,"date":"2026-10-31","provenance":"source"},"kev":{"dateAdded":"2025-03-13","dueDate":"2025-04-03","ransomware":false,"requiredAction":"Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.","notes":"https://supportportal.juniper.net/s/article/2025-03-Out-of-Cycle-Security-Bulletin-Junos-OS-A-local-attacker-with-shell-access-can-execute-arbitrary-code-CVE-2025-21590?language=en_US ; https://nvd.nist.gov/vuln/detail/CVE-2025-21590","provenance":"source"},"vulncheckKev":{"dateAdded":"2025-03-12","exploitedFirstSeen":"2025-03-12","ransomware":false,"evidence":[{"url":"https://cloud.google.com/blog/topics/threat-intelligence/china-nexus-espionage-targets-juniper-routers","date":"2025-03-12"},{"url":"https://supportportal.juniper.net/s/article/2025-03-Reference-Advisory-The-RedPenguin-Malware-Incident","date":"2025-03-12"},{"url":"https://www.cisa.gov/sites/default/files/feeds/known_exploited_vulnerabilities.json","date":"2025-03-13"},{"url":"https://supportportal.juniper.net/s/article/2025-03-Out-of-Cycle-Security-Bulletin-Junos-OS-A-local-attacker-with-shell-access-can-execute-arbitrary-code-CVE-2025-21590","date":"2025-03-14"},{"url":"https://www.trendmicro.com/en_no/research/25/g/revisiting-unc3886-tactics-to-defend-against-present-risk.html","date":"2025-07-28"},{"url":"https://www.enisa.europa.eu/sites/default/files/2025-10/ENISA%20Threat%20Landscape%202025.pdf","date":"2025-10-09"},{"url":"https://www.loginsoft.com/reports/annually/vulnerability-intelligence-report-2025","date":"2026-01-20"},{"url":"https://www.checkpoint.com/security-report/?flz-category=items&flz-item=report-cyber-security-report-2026","date":"2026-01-28"},{"url":"https://cloud.google.com/blog/topics/threat-intelligence/2025-zero-day-review","date":"2026-03-05"},{"url":"https://socradar.io/wp-content/uploads/2026/07/NATO-Threat-Landscape-Report-2026.pdf","date":"2026-07-10"}],"evidenceTotal":10,"provenance":"source"},"exploited":true,"otx":null,"cwes":[{"id":"CWE-653","name":"Improper Isolation or Compartmentalization"}],"references":[{"url":"https://cloud.google.com/blog/topics/threat-intelligence/china-nexus-espionage-targets-juniper-routers","tags":["Third Party Advisory"]},{"url":"https://supportportal.juniper.net/JSA93446","tags":["Vendor Advisory"]},{"url":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2025-21590","tags":["US Government Resource"]}],"techniques":[{"id":"T1068","name":"Exploitation for Privilege Escalation","tactics":["privilege-escalation"],"provenance":"source","basis":"ctid-kev","bases":["ctid-kev"],"basisDetail":"CTID Mappings Explorer KEV 07/28/2025 (ATT&CK 16.1); capability: Code Injection","mappingType":"exploitation_technique","evidence":[],"comment":"This vulnerability allows for an adversary to escalate their privileges within the system, allowing them to execute arbitrary code.","confidence":"high"},{"id":"T1059","name":"Command and Scripting Interpreter","tactics":["execution"],"provenance":"source","basis":"ctid-kev","bases":["ctid-kev"],"basisDetail":"CTID Mappings Explorer KEV 07/28/2025 (ATT&CK 16.1); capability: Code Injection","mappingType":"primary_impact","evidence":[],"comment":"This vulnerability allows for an adversary to escalate their privileges within the system, allowing them to execute arbitrary code.","confidence":"high"}],"reports":[{"id":"SRC-dd25be603e7a56f986e4","title":"redpenguin-wp-draft-20250311","publisher":"supportportal.juniper.net","url":"https://supportportal.juniper.net/sfc/servlet.shepherd/document/download/069Dp00000FzdmIIAR?operationContext=S1","date":null,"mentions":[{"quote":"At least one vulnerability contributed to the successful attack: a process memory injection issue, CVE-2025-21590, described in the Juniper Security Advisory available at: https://supportportal.juniper.net/JSA93446.","start":1318,"end":1533}]}],"affected":[],"advisories":[],"euvd":{"id":"EUVD-2025-6303","url":"https://euvd.enisa.europa.eu/vulnerability/EUVD-2025-6303","exploited":true,"exploitedSince":"2025-03-13","provenance":"source"},"exploits":[],"exploitSources":null,"exploitRefs":[],"flow":[{"stage":"exploitation","techniques":["T1068"],"provenance":"source"},{"stage":"primary","techniques":["T1059"],"provenance":"source"}],"timeline":[{"date":"2025-03-12","kind":"published","label":"Published (NVD)","url":"https://nvd.nist.gov/vuln/detail/CVE-2025-21590","provenance":"source"},{"date":"2025-03-12","kind":"exploited-reported","label":"Exploitation first reported (VulnCheck KEV evidence)","url":"https://cloud.google.com/blog/topics/threat-intelligence/china-nexus-espionage-targets-juniper-routers","provenance":"source"},{"date":"2025-03-13","kind":"kev","label":"Added to CISA KEV","url":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog","provenance":"source"},{"date":"2025-03-13","kind":"euvd-exploited","label":"ENISA EUVD: exploited","url":"https://euvd.enisa.europa.eu/vulnerability/EUVD-2025-6303","provenance":"source"}],"speed":{"daysToPublicExploit":null,"firstExploitFrom":null,"daysToKev":1},"priority":{"score":57.5,"factors":[{"name":"In a KEV catalog","points":35.0,"detail":"listed in CISA KEV and VulnCheck KEV"},{"name":"Recent KEV listing","points":0.0,"detail":"added 599 days ago"},{"name":"Known ransomware use","points":0.0,"detail":"not known"},{"name":"EPSS percentile","points":15.57,"detail":"percentile 0.7785"},{"name":"Named in threat reports","points":3.87,"detail":"1 report"},{"name":"Public exploit code","points":0.0,"detail":"none found"},{"name":"Mentioned in OTX pulses","points":0.0,"detail":"0 pulses"},{"name":"CVSS severity","points":3.08,"detail":"base score 4.4"},{"name":"End-of-life product","points":0.0,"detail":"supported or unknown"}]}}