VulnerabilityAnalyzed

CVE-2026-21901

MEDIUM 6.7EPSS 0.17%

Does this matter?

Lower severity and a low EPSS score (0.17%). Track it; it rarely justifies an emergency change on its own.

Description

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 4.0: 6.7 MEDIUMCVSS: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/M
EPSS: 0.17% probability · 6th percentile
CISA KEV: Not listed
Weakness: CWE-476
Affected: juniper/junos · juniper/junos os evolved
Source: sirt@juniper.net

References

https://github.com/orangecertcc/security-research/security/advisories/GHSA-g4f7-w2rc-hpj6Mitigation, Exploit, Third Party Advisory
https://supportportal.juniper.net/JSA110072Vendor Advisory
https://github.com/orangecertcc/security-research/security/advisories/GHSA-g4f7-w2rc-hpj6Mitigation, Exploit, Third Party Advisory

Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.