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CVE-2026-21908

HIGH · CVSS 7.1EPSS 0.3%EU EUVD

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.

Key facts

CVSS score
7.1 (v3.1)
Severity
HIGH
CVSS vector
CVSS:3.1/AV:A/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
Weakness (CWE)
CWE-416
EPSS score
0.3% (22th percentile)
In CISA KEV
No
In EU EUVD
Yes (EUVD-2026-2690)
Published
January 15, 2026
NVD last modified
June 17, 2026
Status
Analyzed

EU Vulnerability Database (EUVD)

This vulnerability is also tracked by ENISA as EUVD-2026-2690 in the EU Vulnerability Database. Last updated in EUVD on February 26, 2026.

View on the EU Vulnerability Database

Affected products

  • juniper / junos
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and 1 more…

Certified products that may be affected

1 FIPS 140 or Common Criteria certified product, from automated matching by sec-certs.org.

References

Last updated September 17, 2026 · Source: NVD, CISA KEV, FIRST.org EPSS

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