High [CVE-2026-21908] Use After Free vulnerability was identified in the 802.1X authentication daemon (dot1xd) of Juniper Networks Junos OS and…
This high-severity Juniper Networks advisory covers CVE-2026-21908 affecting Junos, Junos OS, Junos OS Evolved.
Android app · Google Play
Monitor future Juniper Networks CVEs from your phone.
Choose a whole vendor or a precise platform, then receive matching security advisories by phone notification, email, or both. Coverage follows 32 official vendor sources and 160+ reviewed platform categories.
Summary
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.
- from 23.2R2-S1 before 23.2R2-S5,
- from 23.4R2 before 23.4R2-S6,
Affected products named by the advisory: EX.
- 24.2
- 24.4
- 25.2
Official advisory · high-confidence parse· fetched 2 months ago·verify at source
- 23.2R2-S5
- 23.4R2-S6
- 24.2R2-S3
- 24.4R2-S1
- 25.2R1-S2
- 23.2R2-S5-EVO
- 23.4R2-S6-EVO
- 24.2R2-S3-EVO
- 24.4R2-S1-EVO
- 25.2R1-S2-EVO
Official advisory · high-confidence parse· fetched 2 months ago·verify at source
Mitigation
Upgrade to a fixed release: 23.2R2-S5, 23.4R2-S6, 24.2R2-S3, 24.4R2-S1, 25.2R1-S2, 23.2R2-S5-EVO. That is the remediation for this advisory.
The vendor advisory may list additional interim mitigations or workarounds not captured here — review it before change work.
Official advisory · high-confidence parse· fetched 2 months ago·verify at source
Discussion(0)
No comments yet. Share field notes, upgrade gotchas, or questions — verify against the vendor advisory before acting on community advice.
Sign in to join the discussion.