CVE-2026-21809

LOWPre-NVD 3.93.9—
EchelonGraph scoreHIGH confidence

Score 3.9 from GitHub Security Advisory (severity: LOW) published 2026-08-27. a secondary CVSS source baseline 3.9; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, secondary
Trending — 4 sources updated this week
3.9EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 3.9Exploit: None knownExposed: 0

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

HCL BigFix Quantum Risk Analyzer has a certain validation process that provides overly descriptive error messages when it encounters malformed input which can allow an attacker to conduct more efficient reconnaissance and fine-tune automated fuzzing tools to produce valid input.

CVSS v3
3.9
EG Score
3.9(high)
EG Risk
18(Track)
EG Risk 18/100SSVC: 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
Severity39% × 45%
Exploitation0% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
1%
KEV
Not listed

Published

August 26, 2026

Last Modified

August 28, 2026

References (1)

Vendor Advisories for CVE-2026-21809(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 10× in last 7d / 10× 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 01:22 UTCEPSS rescore
  2. 2026-08-28 16:13 UTCGHSA enrichment
  3. 2026-08-27 17:20 UTCEG score recompute
  4. 2026-08-27 17:20 UTCGHSA enrichment
  5. 2026-08-27 17:07 UTCEG score recompute
  6. 2026-08-27 17:07 UTCGHSA enrichment
  7. 2026-08-27 14:25 UTCEPSS rescore
  8. 2026-08-26 22:24 UTCEG score recompute
  9. 2026-08-26 22:03 UTCEG score recompute
  10. 2026-08-26 22:01 UTCMITRE cvelistV5first tracked

Frequently asked(5)

What is CVE-2026-21809?
CVE-2026-21809 is a low vulnerability published on August 26, 2026. HCL BigFix Quantum Risk Analyzer has a certain validation process that provides overly descriptive error messages when it encounters malformed input which can allow an attacker to conduct more efficient reconnaissance and fine-tune automated fuzzing tools to produce valid input.
When was CVE-2026-21809 disclosed?
CVE-2026-21809 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-2026-21809 actively exploited?
CVE-2026-21809 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 99.5% of all scored CVEs.
What is the CVSS score of CVE-2026-21809?
CVE-2026-21809 has a CVSS v3 base score of 3.9 (NVD).
How do I remediate CVE-2026-21809?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-21809, 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

Explore the affected products and dependency analysis for CVE-2026-21809

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