{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-21912","assignerOrgId":"8cbe9d5a-a066-4c94-8978-4b15efeae968","state":"PUBLISHED","assignerShortName":"juniper","dateReserved":"2026-01-05T17:32:48.710Z","datePublished":"2026-01-15T20:24:20.087Z","dateUpdated":"2026-01-15T20:50:28.949Z"},"containers":{"cna":{"affected":[{"defaultStatus":"unaffected","platforms":["MX10k Series"],"product":"Junos OS","vendor":"Juniper Networks","versions":[{"lessThan":"21.2R3-S10","status":"affected","version":"0","versionType":"semver"},{"lessThan":"21.4R3-S9","status":"affected","version":"21.4","versionType":"semver"},{"lessThan":"22.2R3-S7","status":"affected","version":"22.2","versionType":"semver"},{"lessThan":"22.4R3-S6","status":"affected","version":"22.4","versionType":"semver"},{"lessThan":"23.2R2-S2","status":"affected","version":"23.2","versionType":"semver"},{"lessThan":"23.4R2-S3","status":"affected","version":"23.4","versionType":"semver"},{"lessThan":"24.2R2","status":"affected","version":"24.2","versionType":"semver"}]}],"datePublic":"2026-01-14T17:00:00.000Z","descriptions":[{"lang":"en","supportingMedia":[{"base64":false,"type":"text/html","value":"A Time-of-check Time-of-use (TOCTOU) Race Condition vulnerability in the method to collect FPC Ethernet firmware statistics of Juniper Networks Junos OS on MX10k Series allows a local, low-privileged attacker executing the 'show system firmware' CLI command to cause an LC480 or LC2101 line card to reset.

On MX10k Series systems with LC480 or LC2101 line cards, repeated execution of the 'show system firmware' CLI command can cause the line card to crash and restart. Additionally, some time after the line card crashes, chassisd may also crash and restart, generating a core dump.

This issue affects Junos OS on MX10k Series: 

"}],"value":"A Time-of-check Time-of-use (TOCTOU) Race Condition vulnerability in the method to collect FPC Ethernet firmware statistics of Juniper Networks Junos OS on MX10k Series allows a local, low-privileged attacker executing the 'show system firmware' CLI command to cause an LC480 or LC2101 line card to reset.\n\nOn MX10k Series systems with LC480 or LC2101 line cards, repeated execution of the 'show system firmware' CLI command can cause the line card to crash and restart. Additionally, some time after the line card crashes, chassisd may also crash and restart, generating a core dump.This issue affects Junos OS on MX10k Series: \n\n\n\n * all versions before 21.2R3-S10, \n * from 21.4 before 21.4R3-S9, \n * from 22.2 before 22.2R3-S7, \n * from 22.4 before 22.4R3-S6, \n * from 23.2 before 23.2R2-S2, \n * from 23.4 before 23.4R2-S3, \n * from 24.2 before 24.2R2."}],"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":"LOCAL","availabilityImpact":"HIGH","baseScore":5.5,"baseSeverity":"MEDIUM","confidentialityImpact":"NONE","integrityImpact":"NONE","privilegesRequired":"LOW","scope":"UNCHANGED","userInteraction":"NONE","vectorString":"CVSS:3.1/AV:L/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":"AUTOMATIC","Safety":"NOT_DEFINED","attackComplexity":"LOW","attackRequirements":"NONE","attackVector":"LOCAL","baseScore":6.8,"baseSeverity":"MEDIUM","privilegesRequired":"LOW","providerUrgency":"AMBER","subAvailabilityImpact":"LOW","subConfidentialityImpact":"NONE","subIntegrityImpact":"NONE","userInteraction":"NONE","valueDensity":"NOT_DEFINED","vectorString":"CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:L/AU:Y/R:A/RE:M/U:Amber","version":"4.0","vulnAvailabilityImpact":"HIGH","vulnConfidentialityImpact":"NONE","vulnIntegrityImpact":"NONE","vulnerabilityResponseEffort":"MODERATE"},"format":"CVSS","scenarios":[{"lang":"en","value":"GENERAL"}]}],"problemTypes":[{"descriptions":[{"cweId":"CWE-367","description":"CWE-367 Time-of-check Time-of-use (TOCTOU) Race Condition","lang":"en","type":"CWE"}]}],"providerMetadata":{"orgId":"8cbe9d5a-a066-4c94-8978-4b15efeae968","shortName":"juniper","dateUpdated":"2026-01-15T20:24:20.087Z"},"references":[{"tags":["vendor-advisory"],"url":"https://supportportal.juniper.net/JSA106011"},{"tags":["vendor-advisory"],"url":"https://kb.juniper.net/JSA106011"}],"solutions":[{"lang":"en","supportingMedia":[{"base64":false,"type":"text/html","value":"The following software releases have been updated to resolve this specific issue: Junos OS 21.2R3-S10, 21.4R3-S9, 22.2R3-S7, 22.4R3-S6, 23.2R2-S2, 23.4R2-S3, 24.2R2, 24.4R1, and all subsequent releases."}],"value":"The following software releases have been updated to resolve this specific issue: Junos OS 21.2R3-S10, 21.4R3-S9, 22.2R3-S7, 22.4R3-S6, 23.2R2-S2, 23.4R2-S3, 24.2R2, 24.4R1, and all subsequent releases."}],"source":{"advisory":"JSA106011","defect":["1695340","1696186"],"discovery":"USER"},"title":"Junos OS: MX10k Series: 'show system firmware' CLI command may lead to LC480 or LC2101 line card reset","workarounds":[{"lang":"en","supportingMedia":[{"base64":false,"type":"text/html","value":"Use CLI authorization to limit access to the 'show system firmware' command."}],"value":"Use CLI authorization to limit access to the 'show system firmware' command."}],"x_generator":{"engine":"Vulnogram 0.1.0-dev"}},"adp":[{"metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-01-15T20:50:22.948273Z","id":"CVE-2026-21912","options":[{"Exploitation":"none"},{"Automatable":"no"},{"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":"2026-01-15T20:50:28.949Z"}}]}}