{"id":"CVE-2026-21908","aliases":["EUVD-2026-2690","GHSA-h976-gqwv-338w"],"status":"published","title":"Junos OS and Junos OS Evolved: Use after free vulnerability In 802.1X authentication daemon can cause crash of the dot1xd process","description":"A Use After Free vulnerability was identified in the 802.1X authentication daemon (dot1xd) of Juniper Networks Junos OS and Junos OS Evolved that could allow an authenticated, network-adjacent attacker flapping a port to crash the dot1xd process, leading to a Denial of Service (DoS), or potentially execute arbitrary code within the context of the process running as root.\n\nThe issue is specific to the processing of a change in authorization (CoA) when a port bounce occurs. A pointer is freed but was then referenced later in the same code path. Successful exploitation is outside the attacker's direct control due to the specific timing of the two events required to execute the vulnerable code path.\n\nThis issue affects systems with 802.1X authentication port-based network access control (PNAC) enabled.\nThis issue affects:\n\nJunos OS: \n\n\n\n  *  from 23.2R2-S1 before 23.2R2-S5, \n  *  from 23.4R2 before 23.4R2-S6, \n  *  from 24.2 before 24.2R2-S3, \n  *  from 24.4 before 24.4R2-S1, \n  *  from 25.2 before 25.2R1-S2, 25.2R2; \n\n\n\n\nJunos OS Evolved: \n\n\n\n  *  from 23.2R2-S1 before 23.2R2-S5-EVO, \n  *  from 23.4R2 before 23.4R2-S6-EVO, \n  *  from 24.2 before 24.2R2-S3-EVO, \n  *  from 24.4 before 24.4R2-S1-EVO, \n  *  from 25.2 before 25.2R1-S2-EVO, 25.2R2-EVO.","severity":{"version":"4.0","score":7.5,"vector":"CVSS:4.0/AV:A/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:L/RE:M/U:Green","level":"high","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-10","score":0.0031,"percentile":0.24133,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":false},"cwes":["CWE-416"],"published":"2026-01-15T20:21:41Z","modified":"2026-06-17T10:19:08Z","products":[{"vendor":"juniper","product":"junos"},{"vendor":"juniper","product":"junos_os_evolved"},{"vendor":"juniper networks","product":"junos os"},{"vendor":"juniper networks","product":"junos os evolved"}],"references":[{"url":"https://supportportal.juniper.net/JSA106007","tags":["vendor-advisory","Vendor Advisory"]},{"url":"https://kb.juniper.net/JSA106007","tags":["vendor-advisory","Vendor Advisory"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-21908"},{"url":"https://github.com/advisories/GHSA-h976-gqwv-338w"}],"sources":{"cve":[{"id":"CVE-2026-21908","title":"Junos OS and Junos OS Evolved: Use after free vulnerability In 802.1X authentication daemon can cause crash of the dot1xd process","description":"A Use After Free vulnerability was identified in the 802.1X authentication daemon (dot1xd) of Juniper Networks Junos OS and Junos OS Evolved that could allow an authenticated, network-adjacent attacker flapping a port to crash the dot1xd process, leading to a Denial of Service (DoS), or potentially execute arbitrary code within the context of the process running as root.\n\nThe issue is specific to the processing of a change in authorization (CoA) when a port bounce occurs. A pointer is freed but was then referenced later in the same code path. Successful exploitation is outside the attacker's direct control due to the specific timing of the two events required to execute the vulnerable code path.\n\nThis issue affects systems with 802.1X authentication port-based network access control (PNAC) enabled.\nThis issue affects:\n\nJunos OS: \n\n\n\n  *  from 23.2R2-S1 before 23.2R2-S5, \n  *  from 23.4R2 before 23.4R2-S6, \n  *  from 24.2 before 24.2R2-S3, \n  *  from 24.4 before 24.4R2-S1, \n  *  from 25.2 before 25.2R1-S2, 25.2R2; \n\n\n\n\nJunos OS Evolved: \n\n\n\n  *  from 23.2R2-S1 before 23.2R2-S5-EVO, \n  *  from 23.4R2 before 23.4R2-S6-EVO, \n  *  from 24.2 before 24.2R2-S3-EVO, \n  *  from 24.4 before 24.4R2-S1-EVO, \n  *  from 25.2 before 25.2R1-S2-EVO, 25.2R2-EVO.","status":"published","published":"2026-01-15T20:21:41.576Z","modified":"2026-02-26T15:04:06.477Z","cvss":[{"version":"4.0","score":7.5,"vector":"CVSS:4.0/AV:A/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:L/RE:M/U:Green","level":"high","assessor":"cna"},{"version":"3.1","score":7.1,"vector":"CVSS:3.1/AV:A/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H","level":"high","assessor":"cna"}],"cwes":["CWE-416"],"updated_at":"2026-11-02T13:41:42.05254Z"}],"euvd":[{"id":"EUVD-2026-2690","description":"A Use After Free vulnerability was identified in the 802.1X authentication daemon (dot1xd) of Juniper Networks Junos OS and Junos OS Evolved that could allow an authenticated, network-adjacent attacker flapping a port to crash the dot1xd process, leading to a Denial of Service (DoS), or potentially execute arbitrary code within the context of the process running as root.\n\nThe issue is specific to the processing of a change in authorization (CoA) when a port bounce occurs. A pointer is freed but was then referenced later in the same code path. Successful exploitation is outside the attacker's direct control due to the specific timing of the two events required to execute the vulnerable code path.\n\nThis issue affects systems with 802.1X authentication port-based network access control (PNAC) enabled.\nThis issue affects:\n\nJunos OS: \n\n\n\n  *  from 23.2R2-S1 before 23.2R2-S5, \n  *  from 23.4R2 before 23.4R2-S6, \n  *  from 24.2 before 24.2R2-S3, \n  *  from 24.4 before 24.4R2-S1, \n  *  from 25.2 before 25.2R1-S2, 25.2R2; \n\n\n\n\nJunos OS Evolved: \n\n\n\n  *  from 23.2R2-S1 before 23.2R2-S5-EVO, \n  *  from 23.4R2 before 23.4R2-S6-EVO, \n  *  from 24.2 before 24.2R2-S3-EVO, \n  *  from 24.4 before 24.4R2-S1-EVO, \n  *  from 25.2 before 25.2R1-S2-EVO, 25.2R2-EVO.","status":"published","published":"2026-01-15T20:21:41Z","modified":"2026-02-26T15:04:06Z","cvss":[{"version":"4.0","score":7.5,"vector":"CVSS:4.0/AV:A/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:L/RE:M/U:Green","level":"high"}],"updated_at":"2026-11-02T19:48:27.038974Z"}],"ghsa":[{"id":"GHSA-h976-gqwv-338w","title":"A Use After Free vulnerability was identified in the 802.1X authentication daemon (dot1xd) of...","description":"A Use After Free vulnerability was identified in the 802.1X authentication daemon (dot1xd) of Juniper Networks Junos OS and Junos OS Evolved that could allow an authenticated, network-adjacent attacker flapping a port to crash the dot1xd process, leading to a Denial of Service (DoS), or potentially execute arbitrary code within the context of the process running as root.\n\nThe issue is specific to the processing of a change in authorization (CoA) when a port bounce occurs. A pointer is freed but was then referenced later in the same code path. Successful exploitation is outside the attacker's direct control due to the specific timing of the two events required to execute the vulnerable code path.\n\nThis issue affects systems with 802.1X authentication port-based network access control (PNAC) enabled.\nThis issue affects:\n\nJunos OS: \n\n\n\n  *  from 23.2R2-S1 before 23.2R2-S5, \n  *  from 23.4R2 before 23.4R2-S6, \n  *  from 24.2 before 24.2R2-S3, \n  *  from 24.4 before 24.4R2-S1, \n  *  from 25.2 before 25.2R1-S2, 25.2R2; \n\n\n\n\nJunos OS Evolved: \n\n\n\n  *  from 23.2R2-S1 before 23.2R2-S5-EVO, \n  *  from 23.4R2 before 23.4R2-S6-EVO, \n  *  from 24.2 before 24.2R2-S3-EVO, \n  *  from 24.4 before 24.4R2-S1-EVO, \n  *  from 25.2 before 25.2R1-S2-EVO, 25.2R2-EVO.","status":"published","published":"2026-01-15T21:31:48Z","modified":"2026-01-15T21:31:55Z","cvss":[{"version":"4.0","score":7.5,"vector":"CVSS:4.0/AV:A/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/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:X/R:X/V:X/RE:M/U:Green","level":"high"},{"version":"3.1","score":7.1,"vector":"CVSS:3.1/AV:A/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H","level":"high"}],"cwes":["CWE-416"],"updated_at":"2026-11-02T15:05:38.149378Z"}],"nvd":[{"id":"CVE-2026-21908","description":"A Use After Free vulnerability was identified in the 802.1X authentication daemon (dot1xd) of Juniper Networks Junos OS and Junos OS Evolved that could allow an authenticated, network-adjacent attacker flapping a port to crash the dot1xd process, leading to a Denial of Service (DoS), or potentially execute arbitrary code within the context of the process running as root.\n\nThe issue is specific to the processing of a change in authorization (CoA) when a port bounce occurs. A pointer is freed but was then referenced later in the same code path. Successful exploitation is outside the attacker's direct control due to the specific timing of the two events required to execute the vulnerable code path.\n\nThis issue affects systems with 802.1X authentication port-based network access control (PNAC) enabled.\nThis issue affects:\n\nJunos OS: \n\n\n\n  *  from 23.2R2-S1 before 23.2R2-S5, \n  *  from 23.4R2 before 23.4R2-S6, \n  *  from 24.2 before 24.2R2-S3, \n  *  from 24.4 before 24.4R2-S1, \n  *  from 25.2 before 25.2R1-S2, 25.2R2; \n\n\n\n\nJunos OS Evolved: \n\n\n\n  *  from 23.2R2-S1 before 23.2R2-S5-EVO, \n  *  from 23.4R2 before 23.4R2-S6-EVO, \n  *  from 24.2 before 24.2R2-S3-EVO, \n  *  from 24.4 before 24.4R2-S1-EVO, \n  *  from 25.2 before 25.2R1-S2-EVO, 25.2R2-EVO.","status":"published","published":"2026-01-15T21:16:06.537Z","modified":"2026-06-17T10:19:08.07Z","cvss":[{"version":"4.0","score":7.5,"vector":"CVSS:4.0/AV:A/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/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:X/R:X/V:X/RE:M/U:Green","level":"high","assessor":"secondary"},{"version":"3.1","score":7.1,"vector":"CVSS:3.1/AV:A/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H","level":"high","assessor":"secondary"}],"cwes":["CWE-416"],"updated_at":"2026-11-02T14:12:04.066712Z"}]}}