{"id":"CVE-2026-21911","aliases":["EUVD-2026-2699","GHSA-6fvr-r66p-5w4v"],"status":"published","title":"Junos OS Evolved: Flapping management interface causes MAC learning on label-switched interfaces to stop","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 flood 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: \n\n  *  all versions before 21.4R3-S7-EVO, \n  *  from 22.2 before 22.2R3-S4-EVO, \n  *  from 22.3 before 22.3R3-S3-EVO, \n  *  from 22.4 before 22.4R3-S2-EVO, \n  *  from 23.2 before 23.2R2-S1-EVO, \n  *  from 23.4 before 23.4R1-S2-EVO, 23.4R2-EVO.","severity":{"version":"4.0","score":7.1,"vector":"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/AU:Y/R:A/V:C/RE:M/U:Amber","level":"high","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-11","score":0.00239,"percentile":0.15053,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":false},"cwes":["CWE-682"],"published":"2026-01-15T20:23:54Z","modified":"2026-06-17T10:19:08Z","products":[{"vendor":"juniper","product":"junos_os_evolved"},{"vendor":"juniper networks","product":"junos os evolved"}],"references":[{"url":"https://supportportal.juniper.net/JSA106010","tags":["vendor-advisory","Vendor Advisory"]},{"url":"https://kb.juniper.net/JSA106010","tags":["vendor-advisory","Vendor Advisory"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-21911"},{"url":"https://github.com/advisories/GHSA-6fvr-r66p-5w4v"}],"sources":{"cve":[{"id":"CVE-2026-21911","title":"Junos OS Evolved: Flapping management interface causes MAC learning on label-switched interfaces to stop","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 flood 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: \n\n  *  all versions before 21.4R3-S7-EVO, \n  *  from 22.2 before 22.2R3-S4-EVO, \n  *  from 22.3 before 22.3R3-S3-EVO, \n  *  from 22.4 before 22.4R3-S2-EVO, \n  *  from 23.2 before 23.2R2-S1-EVO, \n  *  from 23.4 before 23.4R1-S2-EVO, 23.4R2-EVO.","status":"published","published":"2026-01-15T20:23:54.924Z","modified":"2026-01-15T20:51:32.531Z","cvss":[{"version":"4.0","score":7.1,"vector":"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/AU:Y/R:A/V:C/RE:M/U:Amber","level":"high","assessor":"cna"},{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"medium","assessor":"cna"}],"cwes":["CWE-682"],"updated_at":"2026-11-02T13:41:42.05254Z"}],"euvd":[{"id":"EUVD-2026-2699","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 flood 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: \n\n  *  all versions before 21.4R3-S7-EVO, \n  *  from 22.2 before 22.2R3-S4-EVO, \n  *  from 22.3 before 22.3R3-S3-EVO, \n  *  from 22.4 before 22.4R3-S2-EVO, \n  *  from 23.2 before 23.2R2-S1-EVO, \n  *  from 23.4 before 23.4R1-S2-EVO, 23.4R2-EVO.","status":"published","published":"2026-01-15T20:23:54Z","modified":"2026-01-15T20:51:32Z","cvss":[{"version":"4.0","score":7.1,"vector":"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/AU:Y/R:A/V:C/RE:M/U:Amber","level":"high"}],"updated_at":"2026-11-02T19:48:51.36047Z"}],"ghsa":[{"id":"GHSA-6fvr-r66p-5w4v","title":"An Incorrect Calculation vulnerability in the Layer 2 Control\n\nProtocol \n\n Daemon (l2cpd) of...","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 flood 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: \n\n  *  all versions before 21.4R3-S7-EVO, \n  *  from 22.2 before 22.2R3-S4-EVO, \n  *  from 22.3 before 22.3R3-S3-EVO, \n  *  from 22.4 before 22.4R3-S2-EVO, \n  *  from 23.2 before 23.2R2-S1-EVO, \n  *  from 23.4 before 23.4R1-S2-EVO, 23.4R2-EVO.","status":"published","published":"2026-01-15T21:31:48Z","modified":"2026-01-15T21:31:55Z","cvss":[{"version":"4.0","score":7.1,"vector":"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","level":"high"},{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"medium"}],"cwes":["CWE-682"],"updated_at":"2026-11-02T15:05:38.149378Z"}],"nvd":[{"id":"CVE-2026-21911","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 flood 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: \n\n  *  all versions before 21.4R3-S7-EVO, \n  *  from 22.2 before 22.2R3-S4-EVO, \n  *  from 22.3 before 22.3R3-S3-EVO, \n  *  from 22.4 before 22.4R3-S2-EVO, \n  *  from 23.2 before 23.2R2-S1-EVO, \n  *  from 23.4 before 23.4R1-S2-EVO, 23.4R2-EVO.","status":"published","published":"2026-01-15T21:16:07.11Z","modified":"2026-06-17T10:19:08.587Z","cvss":[{"version":"4.0","score":7.1,"vector":"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","level":"high","assessor":"secondary"},{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"medium","assessor":"secondary"}],"cwes":["CWE-682"],"updated_at":"2026-11-02T14:12:04.066712Z"}]}}