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Advisory severityHigh7.1Juniper Networks

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; related products: Junos, Junos OS, Junos OS Evolved.

Aggregated and source-linked by VulniPulse. Data sources, validation and limitations.

CVE-2026-21908 Source published Source updated

VulniPulse record published Record updated

CVE-2026-21908
Related products & platforms
Juniper NetworksSwitchesJunosJunos OS EvolvedEX / QFX Switches
Open source advisory

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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.

Affected versions
  • 24.2
  • 24.4
  • 25.2

Official advisory · high-confidence parse· fetched 4 months ago·verify at source

Fixed versions
  • 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 4 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 4 months ago·verify at source

Discussion(0)

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