CVE-2026-21908 (GCVE-0-2026-21908)
Vulnerability from cvelistv5 – Published: 2026-01-15 20:21 – Updated: 2026-01-16 04:55
VLAI?
Title
Junos OS and Junos OS Evolved: Use after free vulnerability In 802.1X authentication daemon can cause crash of the dot1xd process
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.
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.
Severity ?
CWE
- CWE-416 - Use After Free
Assigner
References
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Impacted products
| Vendor | Product | Version | |||||||
|---|---|---|---|---|---|---|---|---|---|
| Juniper Networks | Junos OS |
Affected:
23.2R2-S1 , < 23.2R2-S5
(semver)
Affected: 23.4R2 , < 23.4R2-S6 (semver) Affected: 24.2 , < 24.2R2-S3 (semver) Affected: 24.4 , < 24.4R2-S1 (semver) Affected: 25.2 , < 25.2R1-S2, 25.2R2 (semver) |
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\"version\": \"23.2R2-S1\", \"lessThan\": \"23.2R2-S5-EVO\", \"versionType\": \"semver\"}, {\"status\": \"affected\", \"version\": \"23.4R2\", \"lessThan\": \"23.4R2-S6-EVO\", \"versionType\": \"semver\"}, {\"status\": \"affected\", \"version\": \"24.2\", \"lessThan\": \"24.2R2-S3-EVO\", \"versionType\": \"semver\"}, {\"status\": \"affected\", \"version\": \"24.4\", \"lessThan\": \"24.4R2-S1-EVO\", \"versionType\": \"semver\"}, {\"status\": \"affected\", \"version\": \"25.2\", \"lessThan\": \"25.2R1-S2-EVO, 25.2R2-EVO\", \"versionType\": \"semver\"}], \"defaultStatus\": \"unaffected\"}], \"exploits\": [{\"lang\": \"en\", \"value\": \"Juniper SIRT is not aware of any malicious exploitation of this vulnerability.\", \"supportingMedia\": [{\"type\": \"text/html\", \"value\": \"Juniper SIRT is not aware of any malicious exploitation of this vulnerability.\", \"base64\": false}]}], \"solutions\": [{\"lang\": \"en\", \"value\": \"The following software releases have been updated to resolve this specific issue:\\nJunos OS 23.2R2-S5, 23.4R2-S6, 24.2R2-S3, 24.4R2-S1, 25.2R1-S2, 25.2R2, 25.4R1, and all subsequent releases.\\nJunos OS Evolved:\\u00a023.2R2-S5-EVO, 23.4R2-S6-EVO, 24.2R2-S3-EVO, 24.4R2-S1-EVO, 25.2R1-S2-EVO, 25.2R2-EVO, 25.4R1-EVO,\", \"supportingMedia\": [{\"type\": \"text/html\", \"value\": \"The following software releases have been updated to resolve this specific issue:\u003cbr\u003eJunos OS 23.2R2-S5, 23.4R2-S6, 24.2R2-S3, 24.4R2-S1, 25.2R1-S2, 25.2R2, 25.4R1, and all subsequent releases.\u003cbr\u003eJunos OS Evolved:\u0026nbsp;23.2R2-S5-EVO, 23.4R2-S6-EVO, 24.2R2-S3-EVO, 24.4R2-S1-EVO, 25.2R1-S2-EVO, 25.2R2-EVO, 25.4R1-EVO,\", \"base64\": false}]}], \"datePublic\": \"2026-01-14T17:00:00.000Z\", \"references\": [{\"url\": \"https://supportportal.juniper.net/JSA106007\", \"tags\": [\"vendor-advisory\"]}, {\"url\": \"https://kb.juniper.net/JSA106007\", \"tags\": [\"vendor-advisory\"]}], \"workarounds\": [{\"lang\": \"en\", \"value\": \"There are no known workarounds for this issue.\", \"supportingMedia\": [{\"type\": \"text/html\", \"value\": \"There are no known workarounds for this issue.\", \"base64\": false}]}], \"x_generator\": {\"engine\": \"Vulnogram 0.1.0-dev\"}, \"descriptions\": [{\"lang\": \"en\", \"value\": \"A Use After Free vulnerability was identified in the 802.1X authentication daemon (dot1xd) of\\u00a0Juniper 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.\\n\\nThe 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\u0027s direct control due to the specific timing of the two events required to execute the vulnerable code path.\\n\\nThis issue affects systems with 802.1X authentication port-based network access control (PNAC) enabled.\\nThis issue affects:\\n\\nJunos OS:\\u00a0\\n\\n\\n\\n * from 23.2R2-S1 before 23.2R2-S5,\\u00a0\\n * from 23.4R2 before 23.4R2-S6,\\u00a0\\n * from 24.2 before 24.2R2-S3,\\u00a0\\n * from 24.4 before 24.4R2-S1,\\u00a0\\n * from 25.2 before 25.2R1-S2, 25.2R2;\\u00a0\\n\\n\\n\\n\\nJunos OS Evolved:\\u00a0\\n\\n\\n\\n * from 23.2R2-S1 before 23.2R2-S5-EVO,\\u00a0\\n * from 23.4R2 before 23.4R2-S6-EVO,\\u00a0\\n * from 24.2 before 24.2R2-S3-EVO,\\u00a0\\n * from 24.4 before 24.4R2-S1-EVO,\\u00a0\\n * from 25.2 before 25.2R1-S2-EVO, 25.2R2-EVO.\", \"supportingMedia\": [{\"type\": \"text/html\", \"value\": \"A Use After Free vulnerability was identified in the 802.1X authentication daemon (dot1xd) of\u0026nbsp;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.\u003cbr\u003e\u003cbr\u003eThe 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\u0027s direct control due to the specific timing of the two events required to execute the vulnerable code path.\u003cbr\u003e\u003cbr\u003eThis issue affects systems with 802.1X authentication port-based network access control (PNAC) enabled.\u003cbr\u003e\u003cp\u003eThis issue affects:\u003c/p\u003e\u003cp\u003eJunos OS:\u0026nbsp;\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cul\u003e\u003cli\u003efrom 23.2R2-S1 before 23.2R2-S5,\u0026nbsp;\u003c/li\u003e\u003cli\u003efrom 23.4R2 before 23.4R2-S6,\u0026nbsp;\u003c/li\u003e\u003cli\u003efrom 24.2 before 24.2R2-S3,\u0026nbsp;\u003c/li\u003e\u003cli\u003efrom 24.4 before 24.4R2-S1,\u0026nbsp;\u003c/li\u003e\u003cli\u003efrom 25.2 before 25.2R1-S2, 25.2R2;\u0026nbsp;\u003c/li\u003e\u003c/ul\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eJunos OS Evolved:\u0026nbsp;\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cul\u003e\u003cli\u003efrom 23.2R2-S1 before 23.2R2-S5-EVO,\u0026nbsp;\u003c/li\u003e\u003cli\u003efrom 23.4R2 before 23.4R2-S6-EVO,\u0026nbsp;\u003c/li\u003e\u003cli\u003efrom 24.2 before 24.2R2-S3-EVO,\u0026nbsp;\u003c/li\u003e\u003cli\u003efrom 24.4 before 24.4R2-S1-EVO,\u0026nbsp;\u003c/li\u003e\u003cli\u003efrom 25.2 before 25.2R1-S2-EVO, 25.2R2-EVO.\u003c/li\u003e\u003c/ul\u003e\u003cp\u003e\u003c/p\u003e\", \"base64\": false}]}], \"problemTypes\": [{\"descriptions\": [{\"lang\": \"en\", \"type\": \"CWE\", \"cweId\": \"CWE-416\", \"description\": \"CWE-416 Use After Free\"}]}], \"configurations\": [{\"lang\": \"en\", \"value\": \"This issue requires support for 802.1X be enabled. For example:\\n\\n[protocols dot1x authenticator ...]\", \"supportingMedia\": [{\"type\": \"text/html\", \"value\": \"This issue requires support for 802.1X be enabled. For example:\u003cbr\u003e\u003cbr\u003e\u003ctt\u003e[protocols dot1x authenticator ...]\u003c/tt\u003e\", \"base64\": false}]}], \"providerMetadata\": {\"orgId\": \"8cbe9d5a-a066-4c94-8978-4b15efeae968\", \"shortName\": \"juniper\", \"dateUpdated\": \"2026-01-15T20:21:41.576Z\"}}}",
"cveMetadata": "{\"cveId\": \"CVE-2026-21908\", \"state\": \"PUBLISHED\", \"dateUpdated\": \"2026-01-16T04:55:55.090Z\", \"dateReserved\": \"2026-01-05T17:32:48.710Z\", \"assignerOrgId\": \"8cbe9d5a-a066-4c94-8978-4b15efeae968\", \"datePublished\": \"2026-01-15T20:21:41.576Z\", \"assignerShortName\": \"juniper\"}",
"dataType": "CVE_RECORD",
"dataVersion": "5.2"
}
}
}
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Sightings
| Author | Source | Type | Date |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
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