CVE-2026-21908

Root code execution or daemon crash via use-after-free

Published Jan 15, 2026 · Updated Jan 15, 2026

Use-after-free in dot1xd in Juniper Networks Junos OS and Junos OS Evolved allows remote authenticated users to crash it or execute code. During a Change of Authorization port bounce, the daemon frees a pointer and later dereferences it again in the same code path. Reachability requires enabled 802.1X port-based network access control and specific, attacker-uncontrolled timing between two events; success interrupts authentication or runs code as root.

CVSS severity7.5
High
EPSS probability0.32%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Use-after-free in dot1xd in Juniper Networks Junos OS and Junos OS Evolved allows remote authenticated users to crash it or execute code. During a Change of Authorization port bounce, the daemon frees a pointer and later dereferences it again in the same code path. Reachability requires enabled 802.1X port-based network access control and specific, attacker-uncontrolled timing between two events; success interrupts authentication or runs code as root.

The record

CVE
CVE-2026-21908
Published
Jan 15, 2026
Updated
Jan 15, 2026
Vendor
Juniper Networks
Product
Junos OS Evolved
Classifications
CWE-416, T1499.004
Attack vector
adjacent
Privileges
authenticated

Timeline

How it unfolded

  1. Jan 15, 2026CVE publishedPublication date reported by the CVE source.
  2. Jan 15, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=23.2R2-S1 <23.2R2-S5-EVO
  2. Affected versionversion=23.4R2 <23.4R2-S6-EVO
  3. Affected versionversion=24.2 <24.2R2-S3-EVO
  4. Affected versionversion=24.4 <24.4R2-S1-EVO
  5. Affected versionversion=25.2 <25.2R1-S2-EVO, 25.2R2-EVO

What conditions does exploitation require?

Attack vectoradjacent
Required privilegesauthenticated

What is affected?

Juniper Networks · Junos OS Evolvedversion=23.2R2-S1 <23.2R2-S5-EVO; version=23.4R2 <23.4R2-S6-EVO; version=24.2 <24.2R2-S3-EVO; version=24.4 <24.4R2-S1-EVO; version=25.2 <25.2R1-S2-EVO, 25.2R2-EVO
Juniper Networks · Junos OSversion=23.2R2-S1 <23.2R2-S5; version=23.4R2 <23.4R2-S6; version=24.2 <24.2R2-S3; version=24.4 <24.4R2-S1; version=25.2 <25.2R1-S2, 25.2R2

Published CVSS scores

7.1Juniper Networks, Inc.CVSS:3.1/AV:A/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
7.5Juniper Networks, Inc.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

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectoradjacent
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-416Use After Free
T1499.004Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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