CVE-2026-21908
published 2026-01-15CVE-2026-21908: 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…
PriorityP341high7.1CVSS 3.1
AVAACHPRLUINSUCHIHAH
EPSS
0.29%
21.2th percentile
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.
The 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.
This issue affects systems with 802.1X authentication port-based network access control (PNAC) enabled.
This issue affects:
Junos OS:
* from 23.2R2-S1 before 23.2R2-S5,
* from 23.4R2 before 23.4R2-S6,
* from 24.2 before 24.2R2-S3,
* from 24.4 before 24.4R2-S1,
* from 25.2 before 25.2R1-S2, 25.2R2;
Junos OS Evolved:
* from 23.2R2-S1 before 23.2R2-S5-EVO,
* from 23.4R2 before 23.4R2-S6-EVO,
* from 24.2 before 24.2R2-S3-EVO,
* from 24.4 before 24.4R2-S1-EVO,
* from 25.2 before 25.2R1-S2-EVO, 25.2R2-EVO.
Affected
21 ranges
| Vendor | Product | Version range | Fixed in |
|---|---|---|---|
| juniper | junos | — | — |
| juniper | junos | — | — |
| juniper | junos | — | — |
| juniper | junos | — | — |
| juniper | junos | — | — |
| juniper | junos_os | — | — |
| juniper | junos_os_evolved | — | — |
| juniper | junos_os_evolved | — | — |
| juniper | junos_os_evolved | — | — |
| juniper | junos_os_evolved | — | — |
| juniper | junos_os_evolved | — | — |
| juniper_networks | junos_os | >= 23.2R2-S1 < 23.2R2-S5 | 23.2R2-S5 |
| juniper_networks | junos_os | >= 23.4R2 < 23.4R2-S6 | 23.4R2-S6 |
| juniper_networks | junos_os | >= 24.2 < 24.2R2-S3 | 24.2R2-S3 |
| juniper_networks | junos_os | >= 24.4 < 24.4R2-S1 | 24.4R2-S1 |
| juniper_networks | junos_os | >= 25.2 < 25.2R1-S2, 25.2R2 | 25.2R1-S2, 25.2R2 |
| juniper_networks | junos_os_evolved | >= 23.2R2-S1 < 23.2R2-S5-EVO | 23.2R2-S5-EVO |
| juniper_networks | junos_os_evolved | >= 23.4R2 < 23.4R2-S6-EVO | 23.4R2-S6-EVO |
| juniper_networks | junos_os_evolved | >= 24.2 < 24.2R2-S3-EVO | 24.2R2-S3-EVO |
| juniper_networks | junos_os_evolved | >= 24.4 < 24.4R2-S1-EVO | 24.4R2-S1-EVO |
| juniper_networks | junos_os_evolved | >= 25.2 < 25.2R1-S2-EVO, 25.2R2-EVO | 25.2R1-S2-EVO, 25.2R2-EVO |
CVSS provenance
nvdv3.17.1HIGHCVSS:3.1/AV:A/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
nvdv4.07.5HIGHCVSS: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
Stop checking back — get the weekly exploitation signal.
Every Monday: what got weaponized or added to CISA KEV in the last seven days — each CVE cross-linked to its PoC, Nuclei template, and detection rule. Free, one email a week, unsubscribe in one click.
GHSA
GHSA-h976-gqwv-338w: A Use After Free vulnerability was identified in the 802
ghsa_unreviewed·2026-01-15
CVE-2026-21908 [HIGH] CWE-416 GHSA-h976-gqwv-338w: A Use After Free vulnerability was identified in the 802
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.
The 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.
This issue affects systems with 802.1X authentication port-based network access control (PNAC)
Juniper
CVE-2026-21908: A Use After Free vulnerability was identified in the 802.1X authentication daemon (dot1xd) of Juniper Networks Junos OS and Junos OS Evolved that coul
vendor_juniper·2026-01-15·CVSS 7.1
CVE-2026-21908 [HIGH] CWE-416 CVE-2026-21908: A Use After Free vulnerability was identified in the 802.1X authentication daemon (dot1xd) of Juniper Networks Junos OS and Junos OS Evolved that coul
CVE-2026-21908: 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.
The 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.
This issue affects systems with 802.1X authentication port-based network acces
No detection rules found.
No public exploits indexed.
No writeups or analysis indexed.
2026-01-15
Published