---
cve: "CVE-2026-21901"
severity: "MEDIUM"
cvss: 6.7
epss: "12%"
vendor: "Juniper Networks"
kev: false
exploited: false
published: "2026-07-09 21:16:54"
tags: [cve, security, medium]
source: tsecurity.de CVE-Dossier
exported: "2026-09-02T16:48:48+02:00"
---

# CVE-2026-21901

> 6.7 MEDIUM · 🧪 PoC

## Beschreibung

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.

## CVSS-Vektor

```
CVSS:4.0/AV:L/AC:L/AT:N/PR:H/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/AU:Y/R:A/V:D/RE:M/U:Green
```

| Metrik | Wert | Bewertung |
|---|---|---|
| AV Angriffsvektor | Lokal | good |
| AC Komplexität | Gering | bad |
| PR Privilegien | Hoch | good |
| UI Interaktion | Keine | bad |

## Referenzen

- <https://github.com/orangecertcc/security-research/security/advisories/GHSA-g4f7-w2rc-hpj6>
- <https://supportportal.juniper.net/JSA110072>

---
_Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/cve?cve=CVE-2026-21901) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI BITS_