CVE-2026-21911

{"id": "CVE-2026-21911", "cveTags": [], "metrics": {"cvssMetricV31": [{"type": "Primary", "source": "sirt@juniper.net", "cvssData": {"scope": "UNCHANGED", "version": "3.1", "baseScore": 6.5, "attackVector": "ADJACENT_NETWORK", "baseSeverity": "MEDIUM", "vectorString": "CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H", "integrityImpact": "NONE", "userInteraction": "NONE", "attackComplexity": "LOW", "availabilityImpact": "HIGH", "privilegesRequired": "NONE", "confidentialityImpact": "NONE"}, "impactScore": 3.6, "exploitabilityScore": 2.8}], "cvssMetricV40": [{"type": "Secondary", "source": "sirt@juniper.net", "cvssData": {"Safety": "NOT_DEFINED", "version": "4.0", "Recovery": "AUTOMATIC", "baseScore": 7.1, "Automatable": "YES", "attackVector": "ADJACENT", "baseSeverity": "HIGH", "valueDensity": "CONCENTRATED", "vectorString": "CVSS:4.0/AV:A/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:L/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:A/V:C/RE:M/U:Amber", "exploitMaturity": "NOT_DEFINED", "providerUrgency": "AMBER", "userInteraction": "NONE", "attackComplexity": "LOW", "attackRequirements": "NONE", "privilegesRequired": "NONE", "subIntegrityImpact": "NONE", "vulnIntegrityImpact": "NONE", "integrityRequirement": "NOT_DEFINED", "modifiedAttackVector": "NOT_DEFINED", "subAvailabilityImpact": "LOW", "vulnAvailabilityImpact": "HIGH", "availabilityRequirement": "NOT_DEFINED", "modifiedUserInteraction": "NOT_DEFINED", "modifiedAttackComplexity": "NOT_DEFINED", "subConfidentialityImpact": "NONE", "vulnConfidentialityImpact": "NONE", "confidentialityRequirement": "NOT_DEFINED", "modifiedAttackRequirements": "NOT_DEFINED", "modifiedPrivilegesRequired": "NOT_DEFINED", "modifiedSubIntegrityImpact": "NOT_DEFINED", "modifiedVulnIntegrityImpact": "NOT_DEFINED", "vulnerabilityResponseEffort": "MODERATE", "modifiedSubAvailabilityImpact": "NOT_DEFINED", "modifiedVulnAvailabilityImpact": "NOT_DEFINED", "modifiedSubConfidentialityImpact": "NOT_DEFINED", "modifiedVulnConfidentialityImpact": "NOT_DEFINED"}}]}, "published": "2026-01-15T21:16:07.110", "references": [{"url": "https://kb.juniper.net/JSA106010", "tags": ["Vendor Advisory"], "source": "sirt@juniper.net"}, {"url": "https://supportportal.juniper.net/JSA106010", "tags": ["Vendor Advisory"], "source": "sirt@juniper.net"}], "vulnStatus": "Analyzed", "weaknesses": [{"type": "Primary", "source": "sirt@juniper.net", "description": [{"lang": "en", "value": "CWE-682"}]}], "descriptions": [{"lang": "en", "value": "An Incorrect Calculation vulnerability in the Layer 2 Control\n\nProtocol \n\n Daemon (l2cpd) of Juniper Networks Junos OS Evolved allows an unauthenticated network-adjacent attacker flapping the management interface to cause the learning of new MACs over label-switched interfaces (LSI) to stop while generating a\u00a0flood of logs, resulting in high CPU usage.\n\nWhen the issue is seen, the following log message will be generated:\n\nop:1 flag:0x6 mac:xx:xx:xx:xx:xx:xx bd:2 ifl:13302 reason:0(REASON_NONE) i-op:6(INTRNL_OP_HW_FORCE_DELETE) status:10 lstatus:10 err:26(GETIFBD_VALIDATE_FAILED) err-reason 4(IFBD_VALIDATE_FAIL_EPOCH_MISMATCH) hw_wr:0x4 ctxsync:0 fwdsync:0 rtt-id:51 p_ifl:0 fwd_nh:0 svlbnh:0 event:- smask:0x100000000 dmask:0x0 mplsmask 0x1 act:0x5800 extf:0x0 pfe-id 0 hw-notif-ifl 13302 programmed-ifl 4294967295 pseudo-vtep underlay-ifl-idx 0 stack:GET_MAC, ALLOCATE_MAC, GET_IFL, GET_IFF, GET_IFBD, STOP, \n\n\nThis issue affects Junos OS Evolved:\u00a0\n\n * all versions before 21.4R3-S7-EVO,\u00a0\n * from 22.2 before 22.2R3-S4-EVO,\u00a0\n * from 22.3 before 22.3R3-S3-EVO,\u00a0\n * from 22.4 before 22.4R3-S2-EVO,\u00a0\n * from 23.2 before 23.2R2-S1-EVO,\u00a0\n * from 23.4 before 23.4R1-S2-EVO, 23.4R2-EVO."}], "lastModified": "2026-01-23T16:59:03.777", 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