CVE-2026-21901

MEDIUMPre-NVD 4.44.4
EchelonGraph scoreMEDIUM confidence

“—” beside the score: it is equal to the CVSS score beside it.

This medium-severity CVE scores 4.4 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.2% (5th percentile of EPSS-scored CVEs). No GitHub Security Advisory CVSS is on record for this CVE.

Triggered by: Headline CVSS from a secondary CVSS source
Sources: EPSS, a secondary CVSS source
Elevated
4.4EG
EchelonGraph verdictPlan a fixRemediate within your standard update timelines (the SSVC decision on this page).
  • CISA's Vulnrichment rates exploitation as PoC; EchelonGraph holds no exploit-code reference for it
CISA-KEV: Not listedEPSS PROB: 0.2%CVSS: 4.4Exploit: No code on recordExposed services: Not assessed

The following software releases have been updated to resolve this specific issue: Junos OS: 22.3R3-S5, 22.4R3-S10, 23.2R2-S7, 23.4R2-S8, 24.2R1, and all subsequent releases (from the CVE record's solution, Juniper Networks, Inc.) — apply it.

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 v3
4.4
EG Score
4.4MEDIUMmedium confidence
EG Risk
36
EG Risk 36/100

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed (value × EchelonGraph’s weight)
Severity44% × 45%
The EG Score, 4.4 of 10.
Exploitation40% × 40%
EchelonGraph's fixed weight for EG-KEV Tier 3 (Elevated): a constant, not a probability.
Automatability0% × 15%
CISA's SSVC Automatable value: no (Vulnrichment).
SSVC (CISA's decision table, applied by EchelonGraph): Track at low or medium mission impact; Track* at high (mission-essential systems).
Exploitation public PoC (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE.
Action: The following software releases have been updated to resolve this specific issue: Junos OS: 22.3R3-S5, 22.4R3-S10, 23.2R2-S7, 23.4R2-S8, 24.2R1, and all subsequent releases (from the CVE record's solution, Juniper Networks, Inc.). Apply it within your standard update timelines.
EPSS PROB
0.2%
EPSS %ILE
5th
KEV
Not listed

SSVC (CISA's decision table, applied by EchelonGraph)Track at low or medium mission impact; Track* at high (mission-essential systems).

The following software releases have been updated to resolve this specific issue: Junos OS: 22.3R3-S5, 22.4R3-S10, 23.2R2-S7, 23.4R2-S8, 24.2R1, and all subsequent releases (from the CVE record's solution, Juniper Networks, Inc.). Apply it within your standard update timelines.

Exploitation public PoC (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table

BOD 26-04 (CISA's remediation timeline, Table 1)60 days if the affected system is publicly exposed; Fix on system upgrade if it is not.

In CISA KEV no (CISA's KEV catalog) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it

Published

July 9, 2026

Last Modified

August 26, 2026

Advisory Details (2)

Auto-updated Jul 9, 2026
Fix named in the CVE record's solution (Juniper Networks, Inc.). Sources: github.
Web page

CEC Juniper Community

https://supportportal.juniper.net/JSA110072
GitHub advisoryMentions a patch (unverified)

Juniper Junos - Null pointer reference (CVE-2026-21901) · Advisory · orangecertcc/security-research · GitHub

https://github.com/orangecertcc/security-research/security/advisories/GHSA-g4f7-w2rc-hpj6

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 11× in last 7d / 31× in last 30d)

Each row is a time one of our pipelines fetched, updated or re-scored this CVE. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. An arrow marks a change the record states ("CVSS v3 → 9.1"); EPSS and GHSA rows show the values recorded at that time, not what changed (EPSS values are rounded; hover one for the exact figures). Most recent first.

Showing the most recent 99 of 133 refreshes on record for this CVE.

A repeat, a row identical to one the same pipeline wrote less than 10 seconds earlier, is not a separate refresh and is not counted. 1 repeat row among the latest 100 is merged into the row it repeats. The 34 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

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Frequently asked(5)

What is CVE-2026-21901?
CVE-2026-21901 is a medium-severity vulnerability; its CVE record was published on July 9, 2026. 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…
When was CVE-2026-21901 made public?
CVE-2026-21901 was made public on July 8, 2026: that is the date its CVE record's CNA, Juniper Networks, Inc., gives for when the vulnerability was made public. The CVE record itself was published on July 9, 2026. EchelonGraph's copy of the record carries a last-modified date of August 26, 2026; the record at its source may have been updated since.
Is CVE-2026-21901 actively exploited?
CVE-2026-21901 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.2% probability of exploitation in the next 30 days (5th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-21901?
CVE-2026-21901 has a CVSS base score of 4.4 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-21901?
The CVE record's solution for CVE-2026-21901, written by its CNA Juniper Networks, Inc., names the fix: "The following software releases have been updated to resolve this specific issue: Junos OS: 22.3R3-S5, 22.4R3-S10, 23.2R2-S7, 23.4R2-S8, 24.2R1, and all subsequent releases."

Dependency Blast Radius

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