Junos OS Evolved: Flapping management interface causes MAC learning on label-switched interfaces to stop_CVE-2026-21911

{
    "lastseen": "",
    "description": "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.",
    "published": "2026-01-15T20:23:54.924Z",
    "modified": "2026-01-15T20:51:32.531Z",
    "type": "cve",
    "title": "Junos OS Evolved: Flapping management interface causes MAC learning on label-switched interfaces to stop",
    "source": "juniper",
    "references": "https://supportportal.juniper.net/JSA106010\nhttps://kb.juniper.net/JSA106010",
    "id": "CVE-2026-21911",
    "bulletinFamily": "",
    "cwe": [
        "CWE-682"
    ],
    "cvelist": null,
    "sourceData": "Juniper Networks Junos OS Evolved 0\nJuniper Networks Junos OS Evolved 22.2\nJuniper Networks Junos OS Evolved 22.3\nJuniper Networks Junos OS Evolved 22.4\nJuniper Networks Junos OS Evolved 23.2\nJuniper Networks Junos OS Evolved 23.4",
    "sourceHref": "",
    "cvss": {
        "score": 6.5,
        "severity": "MEDIUM",
        "vector": "CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
        "version": "3.1"
    },
    "cvss2": [],
    "cvss3": {
        "version": "",
        "vectorString": "",
        "baseScore": 0,
        "baseSeverity": "",
        "attackVector": "",
        "attackComplexity": "",
        "privilegesRequired": "",
        "userInteraction": "",
        "scope": "",
        "confidentialityImpact": "",
        "integrityImpact": "",
        "availabilityImpact": "",
        "cvssV3": {
            "version": "",
            "vectorString": "",
            "baseScore": 0,
            "baseSeverity": "",
            "attackVector": "",
            "attackComplexity": "",
            "privilegesRequired": "",
            "userInteraction": "",
            "scope": "",
            "confidentialityImpact": "",
            "integrityImpact": "",
            "availabilityImpact": ""
        }
    },
    "href": "",
    "category_name": "CVE",
    "post_link": "",
    "product": "Junos OS Evolved",
    "version": "0",
    "vendor": "Juniper Networks",
    "ai_description": "",
    "ai_severity": "",
    "ai_vendor": "",
    "ai_product": "",
    "ai_version": "",
    "ai_score": 0
}