CVE-2026-21901

6.7 MEDIUM 0.2% exploit odds Fix listed Memory safety

What it 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.

At a glance

Exploitability: Can be exploited locally on the machine with an admin-level account. High risk of service disruption.
Exploit odds: 0.2% chance of exploitation in the next 30 days (EPSS).
Fix: A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

2026-07-09 21:16 UTC PublishedDisclosed publicly on CVE.org and NVD
2026-08-26 17:48 UTC Last updatedMost recent change to the record

Why it ranks here

Exploited in the wild: no, CISA does not list it.
Exploit odds: 0.2% in the next 30 days (EPSS).
Severity: 6.7 MEDIUM (CVSS).
Fix: a patch or advisory is linked.

Details

Published: 2026-07-09 21:16 UTC
Last modified: 2026-08-26 17:48 UTC
Exploit probability: 0.2% · EPSS, next 30 days
Weakness: CWE-476 · NULL pointer dereference
Record status: Analyzed

Affected

Juniper Junos 22.3
Juniper Junos 22.4
Juniper Junos 23.2
Juniper Junos 23.4
Juniper Junos Os Evolved 22.3
Juniper Junos Os Evolved 22.4
Juniper Junos Os Evolved 23.1
Juniper Junos Os Evolved 23.2

Attack profile CVSS 4.0 · 6.7

Attack vector: Local
Complexity: Low
Attack requirements: None
Privileges needed: High
User interaction: None
Confidentiality: None
Integrity: None
Availability: High

Raw vector

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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:Y/R:A/V:D/RE:M/U:Green

Is it in your code?

Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.

Read https://cve-list.com/agent/cve/CVE-2026-21901.md and follow it. Check whether this project is affected by CVE-2026-21901. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

· More options · Status badge

Download Square Reddit

Fix and advisories

References

NVD record · CVE.org record