CVE-2026-21901

MEDIUMPre-NVD 4.44.4—
EchelonGraph scoreMEDIUM confidence

This medium-severity CVE scores 4.4 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.1%, top 98% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, secondary
Elevated
4.4EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 4.4Exploit: Elevated riskExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

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
4.4(medium)
EG Risk
36(Track)
EG Risk 36/100SSVC: Track

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
Severity44% × 45%
Exploitation40% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
2%
KEV
Not listed

Published

July 9, 2026

Last Modified

July 10, 2026

Advisory Details (2)

Auto-updated Jul 9, 2026
🔬 Proof of concept available. Patch available. Sources: github.
generic

CEC Juniper Community

https://supportportal.juniper.net/JSA110072
github Patch Available🟡 PoC Available

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 12× in last 7d / 40× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. 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. Most recent first.

  1. 2026-07-31 02:24 UTCEG score recompute
  2. 2026-07-30 04:22 UTCEG score recompute
  3. 2026-07-30 01:30 UTCEPSS rescore
  4. 2026-07-29 06:21 UTCEG score recompute
  5. 2026-07-28 08:20 UTCEG score recompute
  6. 2026-07-27 14:13 UTCEPSS rescore
  7. 2026-07-27 10:17 UTCEG score recompute
  8. 2026-07-26 14:54 UTCEPSS rescore
  9. 2026-07-26 14:54 UTCEPSS rescore
  10. 2026-07-26 12:17 UTCEG score recompute
  11. 2026-07-25 14:17 UTCEPSS rescore
  12. 2026-07-25 14:17 UTCEPSS rescore
  13. 2026-07-24 14:17 UTCEPSS rescore
  14. 2026-07-23 14:18 UTCEPSS rescore
  15. 2026-07-23 14:18 UTCEPSS rescore
  16. 2026-07-23 03:06 UTCEG score recompute
  17. 2026-07-22 14:08 UTCEPSS rescore
  18. 2026-07-21 15:24 UTCEPSS rescore
  19. 2026-07-21 15:24 UTCEPSS rescore
  20. 2026-07-20 17:08 UTCEPSS rescore
  21. 2026-07-19 14:31 UTCEPSS rescore
  22. 2026-07-19 14:31 UTCEPSS rescore
  23. 2026-07-19 02:29 UTCEPSS rescore
  24. 2026-07-19 02:28 UTCEPSS rescore
  25. 2026-07-18 10:04 UTCEPSS rescore
Show 15 more
  1. 2026-07-18 10:04 UTCEPSS rescore
  2. 2026-07-16 17:03 UTCEPSS rescore
  3. 2026-07-16 17:03 UTCEPSS rescore
  4. 2026-07-15 16:57 UTCEPSS rescore
  5. 2026-07-15 16:57 UTCEPSS rescore
  6. 2026-07-15 02:00 UTCEPSS rescore
  7. 2026-07-15 02:00 UTCEPSS rescore
  8. 2026-07-13 22:30 UTCEPSS rescore
  9. 2026-07-13 06:13 UTCEPSS rescore
  10. 2026-07-13 06:13 UTCEPSS rescore
  11. 2026-07-12 05:46 UTCEPSS rescore
  12. 2026-07-12 05:46 UTCEPSS rescore
  13. 2026-07-11 08:27 UTCEPSS rescore
  14. 2026-07-09 21:06 UTCEG score recompute
  15. 2026-07-09 21:05 UTCMITRE cvelistV5first tracked

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Frequently asked(5)

What is CVE-2026-21901?
CVE-2026-21901 is a medium vulnerability 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 disclosed?
CVE-2026-21901 was first published in the National Vulnerability Database on July 9, 2026, with the most recent update on July 10, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-21901 actively exploited?
CVE-2026-21901 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 98.0% of all scored CVEs.
What is the CVSS score of CVE-2026-21901?
CVE-2026-21901 has a CVSS v3 base score of 4.4 (NVD).
How do I remediate CVE-2026-21901?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-21901, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

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