CVE-2026-77540

CRITICALPre-NVD 9.19.1—
EchelonGraph scoreHIGH confidence

Score 9.1 from GitHub Security Advisory (severity: CRITICAL) published 2026-08-27. a secondary CVSS source baseline 9.1; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, secondary
Trending — 4 sources updated this week
9.1EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 1%CVSS: 9.1Exploit: None knownExposed: 0

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

A malicious actor with access to the network and high privileges could exploit an Improper Input Validation vulnerability found in UniFi OS Server to execute a Command Injection on the host device.

CVSS v3
9.1
EG Score
9.1(high)
EG Risk
41(Track)
EG Risk 41/100SSVC: 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
Severity91% × 45%
Exploitation1% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
1%
EPSS %ILE
54%
KEV
Not listed

Published

August 26, 2026

Last Modified

August 28, 2026

Advisory Details (1)

Auto-updated Aug 29, 2026
No patch confirmed yet.
generic
https://community.ui.com/releases/Security-Advisory-Bulletin-067/fc4a3488-7c43-4628-8bab-f715e96dbfc9

Vendor Advisories for CVE-2026-77540(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 31× in last 7d / 31× 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. 2026-08-30 04:49 UTCEG score recompute
  2. 2026-08-30 04:49 UTCGHSA enrichment
  3. 2026-08-30 01:22 UTCEPSS rescore
  4. 2026-08-30 00:44 UTCGHSA enrichment
  5. 2026-08-29 20:39 UTCGHSA enrichment
  6. 2026-08-29 16:33 UTCGHSA enrichment
  7. 2026-08-29 12:25 UTCGHSA enrichment
  8. 2026-08-29 08:15 UTCGHSA enrichment
  9. 2026-08-29 04:09 UTCGHSA enrichment
  10. 2026-08-28 23:58 UTCEG score recompute
  11. 2026-08-28 23:58 UTCGHSA enrichment
  12. 2026-08-28 21:42 UTCEPSS rescore
  13. 2026-08-28 19:06 UTCGHSA enrichment
  14. 2026-08-28 17:24 UTCGHSA enrichment
  15. 2026-08-28 13:14 UTCGHSA enrichment
  16. 2026-08-28 09:07 UTCGHSA enrichment
  17. 2026-08-28 04:59 UTCGHSA enrichment
  18. 2026-08-28 00:53 UTCGHSA enrichment
  19. 2026-08-27 20:48 UTCGHSA enrichment
  20. 2026-08-27 16:44 UTCEG score recompute
  21. 2026-08-27 16:43 UTCGHSA enrichment
  22. 2026-08-27 14:25 UTCEPSS rescore
  23. 2026-08-27 12:36 UTCGHSA enrichment
  24. 2026-08-27 08:31 UTCEG score recompute
  25. 2026-08-27 08:31 UTCGHSA enrichment
Show 6 more
  1. 2026-08-27 04:26 UTCEG score recompute
  2. 2026-08-27 04:02 UTCEG score recompute
  3. 2026-08-26 15:54 UTCEG score recompute
  4. 2026-08-26 13:43 UTCEG score recompute
  5. 2026-08-26 10:04 UTCEG score recompute
  6. 2026-08-26 10:02 UTCMITRE cvelistV5first tracked

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-77540?
CVE-2026-77540 is a critical vulnerability published on August 26, 2026. A malicious actor with access to the network and high privileges could exploit an Improper Input Validation vulnerability found in UniFi OS Server to execute a Command Injection on the host device.
When was CVE-2026-77540 disclosed?
CVE-2026-77540 was first published in the National Vulnerability Database on August 26, 2026, with the most recent update on August 28, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-77540 actively exploited?
CVE-2026-77540 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 1% probability of exploitation in the next 30 days, which ranks it in the top 46.0% of all scored CVEs.
What is the CVSS score of CVE-2026-77540?
CVE-2026-77540 has a CVSS v3 base score of 9.1 (NVD).
How do I remediate CVE-2026-77540?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-77540, 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.

Dependency Blast Radius

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