Juniper Junos OS/Junos OS Evolved prior 23.4R2-S8-EVO SSH Configuration null pointer dereference

CVSS Meta Temp Score
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CTI Interest Score
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4.2$0-$5k0.56

Summaryinfo

A vulnerability marked as problematic has been reported in Juniper Junos OS and Junos OS Evolved. Affected by this vulnerability is an unknown functionality of the component SSH Configuration. This manipulation causes null pointer dereference. This vulnerability is handled as CVE-2026-21901. It is possible to launch the attack on the local host. There is not any exploit available.

Detailsinfo

A vulnerability has been found in Juniper Junos OS and Junos OS Evolved and classified as problematic. Affected by this vulnerability is an unknown code of the component SSH Configuration. The manipulation with an unknown input leads to a null pointer dereference vulnerability. The CWE definition for the vulnerability is CWE-476. A NULL pointer dereference occurs when the application dereferences a pointer that it expects to be valid, but is NULL, typically causing a crash or exit. As an impact it is known to affect availability. The summary by CVE is:

A NULL Pointer Dereference vulnerability in the management daemon (mgd) of Juniper Networks Junos OS and Junos OS Evolved allows a local, high-privileged attacker setting or deactivating a specific SSH configuration parameter to create a Denial of Service (DoS). A local high-privileged user configuring or deactivating a specific 'system services ssh' configuration parameter can exploit a null pointer dereference in one of the functions used by SSH. The function attempts to dereference a null pointer when accessing certain configuration data, resulting in an mgd process crash and restart. Continued execution of these configuration commands will create a sustained Denial of Service (DoS) condition. This issue affects: Junos OS: * from 22.3 before 22.3R3-S5; * from 22.4 before 22.4R3-S10; * from 23.2 before 23.2R2-S7; * from 23.4 before 23.4R2-S8. This issue does not affect Junos OS before 22.3R1. Junos OS Evolved: * from 22.3R1-EVO before 23.2R2-S7-EVO; * from 23.4 before 23.4R2-S8-EVO. This issue does not affect Junos OS Evolved before 22.3R1-EVO.

It is possible to read the advisory at github.com. This vulnerability is known as CVE-2026-21901 since 01/05/2026. The exploitation appears to be easy. Attacking locally is a requirement. The exploitation needs additional levels of successful authentication. The technical details are unknown and an exploit is not publicly available.

Upgrading to version 22.3R3-S5, 22.4R3-S10, 23.2R2-S7, 23.4R2-S8, 23.2R2-S7-EVO or 23.4R2-S8-EVO eliminates this vulnerability.

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Productinfo

Type

Vendor

Name

License

Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 4.4
VulDB Meta Temp Score: 4.2

VulDB Base Score: 4.4
VulDB Temp Score: 4.2
VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv2info

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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Null pointer dereference
CWE: CWE-476 / CWE-404
CAPEC: 🔒
ATT&CK: 🔒

Physical: Partially
Local: Yes
Remote: No

Availability: 🔒
Status: Not defined
Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: no mitigation known
Status: 🔍

0-Day Time: 🔒

Upgrade: Junos OS/Junos OS Evolved 22.3R3-S5/22.4R3-S10/23.2R2-S7/23.4R2-S8/23.2R2-S7-EVO/23.4R2-S8-EVO

Timelineinfo

01/05/2026 CVE reserved
07/09/2026 +184 days Advisory disclosed
07/09/2026 +0 days VulDB entry created
07/09/2026 +0 days VulDB entry last update

Sourcesinfo

Vendor: juniper.net

Advisory: github.com
Status: Confirmed

CVE: CVE-2026-21901 (🔒)
GCVE (CVE): GCVE-0-2026-21901
GCVE (VulDB): GCVE-100-377311

Entryinfo

Created: 07/09/2026 23:33
Changes: 07/09/2026 23:33 (53)
Complete: 🔍
Cache ID: 216::103

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