{"id":"CVE-2025-21590","kind":"vulnerability","aliases":["CVE-2025-21590"],"related":[],"title":"juniper junos: An Improper Isolation or Compartmentalization vulnerability in the kernel of Juniper Networks Junos OS allows a…","description":"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.","summary":"Juniper Junos OS, the operating system on Juniper routers and switches, has an improper isolation flaw that lets a local attacker with high privileges inject arbitrary code. CISA lists it as actively exploited in the wild.","severity":"medium","cvss":6.7,"epss":null,"exploited":true,"exploited_at":"2025-03-13T00:00:00+00:00","products":[{"name":"Juniper Junos OS","fixed":[],"affected":"","ecosystem":"vendor"},{"name":"juniper junos","fixed":["21.2"],"affected":"< 21.2","ecosystem":"vendor"},{"name":"juniper junos","fixed":[],"affected":"= 21.2","ecosystem":"vendor"},{"name":"juniper junos","fixed":[],"affected":"= 21.4","ecosystem":"vendor"},{"name":"juniper junos","fixed":[],"affected":"= 22.2","ecosystem":"vendor"},{"name":"juniper junos","fixed":[],"affected":"= 22.4","ecosystem":"vendor"},{"name":"juniper junos","fixed":[],"affected":"= 23.2","ecosystem":"vendor"},{"name":"juniper junos","fixed":[],"affected":"= 23.4","ecosystem":"vendor"},{"name":"juniper junos","fixed":[],"affected":"= 24.2","ecosystem":"vendor"}],"ecosystems":["vendor"],"tags":["exploited","infrastructure","juniper","junos","network-gear"],"not_affected_if":["not-running-junos"],"how_to_check":null,"fix":"Apply mitigations per vendor instructions from Juniper; discontinue use of the product if mitigations are unavailable (per CISA required action).","status":"open","published_at":"2025-03-12T14:15:15+00:00","first_seen_at":"2026-10-23T19:11:51+00:00","triaged_at":"2026-10-23T20:49:00+00:00","updated_at":"2026-10-23T22:29:05+00:00","category":"infrastructure","confidence":0.6,"triage":{"at":"2026-10-23T20:49:00Z","model":"claude-haiku-5-5","output":{"fix":"Apply mitigations per vendor instructions from Juniper; discontinue use of the product if mitigations are unavailable (per CISA required action).","reach":"local","summary":"Juniper Junos OS, the operating system on Juniper routers and switches, has an improper isolation flaw that lets a local attacker with high privileges inject arbitrary code. CISA lists it as actively exploited in the wild.","category":"infrastructure","who_cares":["juniper","junos","network-gear"],"confidence":0.6,"needs_auth":"yes","worst_case":"Attacker with high privileges runs arbitrary code on the device.","analyst_note":"Find the Juniper advisory for CVE-2025-21590 and the affected/fixed Junos versions and mitigation steps; the sources give no version data.","how_to_check":"unknown","needs_analyst":true,"not_affected_if":["not-running-junos"],"user_interaction":"no","needs_special_setup":"unknown","severity_if_unknown":"unknown"},"cost_usd":0.000429,"input_tokens":2546,"output_tokens":348,"severity_before":"unknown"},"analyst_status":null,"analyst_note":null,"search":"'-2025':19A,22A '-21590':20A,23A '21.2':151C '21.4':155C,158C '22.2':162C,165C '22.4':169C,172C '23.2':176C,179C '23.4':183C,186C '24.2':190C,193C,197C 'abl':123C 'access':118C 'activ':81B 'affect':132C,145C 'allow':17A,100C 'arbitrari':75B,126C 'attack':70B,103C,116C 'cisa':77B 'cli':142C 'code':76B,127C 'compartment':7A,90C 'compromis':108C,130C 'cve':18A,21A 'devic':113C,133C 'exploit':43B,82B,138C 'flaw':65B 'gear':49B 'high':72B,105C 'improp':4A,63B,87C 'infrastructur':44B 'inject':74B,125C 'integr':110C 'isol':5A,64B,88C 'issu':135C,144C 'junip':1A,13A,45B,50B,57B,96C 'juniper':24A,27A,29A,31A,33A,35A,37A,39A,41A 'juno':2A,15A,46B,51B,98C,141C,146C 'junos':25A,28A,30A,32A,34A,36A,38A,40A,42A 'kernel':11A,94C 'let':67B 'list':78B 'local':69B,102C,115C 'network':14A,48B,97C 'network-gear':47B 'oper':54B 'os':16A,26A,52B,99C,147C 'privileg':73B,106C 'r1':195C 'r1-s2':194C 'r2':181C,188C,198C 'r2-s3':180C 'r2-s4':187C 'r3':153C,160C,167C,174C 'r3-s10':159C 'r3-s6':166C,173C 'r3-s9':152C 'router':58B 's10':161C 's2':196C 's3':182C 's4':189C 's6':168C,175C 's9':154C 'shell':121C 'switch':60B 'system':55B 'version':149C,156C,163C,170C,177C,184C,191C 'vulner':8A,91C 'wild':85B","nicknames":[],"mitigations":[],"who_affected":null,"tier":null,"verified":{},"analyst_revisit_at":null,"first_public_at":"2025-03-12T14:15:15+00:00","kev":{"dateAdded":"2025-03-13","dueDate":"2025-04-03","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.","knownRansomwareCampaignUse":"Unknown"},"cvss_vector":"CVSS:4.0/AV:L/AC:L/AT:N/PR:H/UI:N/VC:N/VI:H/VA:N/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:X/R:X/V:X/RE:X/U:X","cvss_by":"sirt@juniper.net","poc_count":0,"sources":[{"source":"kev","external_id":"CVE-2025-21590","url":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog?search_api_fulltext=CVE-2025-21590","severity":null,"published_at":"2025-03-13T00:00:00+00:00","modified_at":null,"first_seen_at":"2026-10-23T19:11:51+00:00","fetched_at":"2026-10-25T13:39:29+00:00","note":null},{"source":"nvd","external_id":"CVE-2025-21590","url":"https://nvd.nist.gov/vuln/detail/CVE-2025-21590","severity":null,"published_at":"2025-03-12T14:15:15+00:00","modified_at":"2026-10-01T18:23:34+00:00","first_seen_at":"2026-10-23T22:29:05+00:00","fetched_at":"2026-10-23T22:29:05+00:00","note":null}],"documents":[],"notice":"Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai"}