CVE-2021-38156

CRITICALNVD 5.49.0▲
EchelonGraph scoreHIGH confidence

Score elevated to 9.0 because EPSS predicts 89% probability of exploitation within the next 30 days (top 0.2% of all CVEs). NVD baseline CVSS 5.4 retained for reference. Confidence: see factors.

Triggered by: EPSS exploit prediction ≥85%
Sources: epss, nvd
Elevated
9.0EG
EchelonGraph verdictPatch this weekExploitation is likely or a public exploit exists.
  • High exploitation likelihood — EPSS 89%
CISA-KEV: Not listedEPSS PROB: 89%CVSS: 5.4Exploit: Elevated riskExposed: 0

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

In Nagios XI before 5.8.6, XSS exists in the dashboard page (/dashboards/#) when administrative users attempt to edit a dashboard.

CVSS v3
5.4
EG Score
9.0(high)
EG Risk
81(Track)
EG Risk 81/100SSVC: 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
Severity90% × 45%
Exploitation89% × 40%
Automatability30% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
89%
EPSS %ILE
100%
KEV
Not listed

Published

September 15, 2021

Last Modified

November 21, 2024

References (4)

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 3× in last 7d / 13× 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. 2026-09-06 13:45 UTCEPSS rescore
  2. 2026-09-06 13:45 UTCEPSS rescore
  3. 2026-09-05 15:25 UTCEPSS rescore
  4. 2026-08-30 19:14 UTCEPSS rescore
  5. 2026-08-28 21:37 UTCEPSS rescore
  6. 2026-08-27 14:22 UTCEPSS rescore
  7. 2026-08-26 14:42 UTCEPSS rescore
  8. 2026-08-24 14:13 UTCEPSS rescore
  9. 2026-08-21 23:46 UTCEPSS rescore
  10. 2026-08-16 02:11 UTCEPSS rescore
  11. 2026-08-16 02:11 UTCEPSS rescore
  12. 2026-08-12 13:48 UTCEPSS rescore
  13. 2026-08-11 13:38 UTCEPSS rescore
  14. 2026-08-08 16:33 UTCEPSS rescore
  15. 2026-08-06 13:43 UTCEPSS rescore
  16. 2026-08-05 19:14 UTCEPSS rescore
  17. 2026-08-04 15:06 UTCEPSS rescore
  18. 2026-07-28 15:33 UTCEPSS rescore
  19. 2026-07-25 14:15 UTCEPSS rescore
  20. 2026-07-24 14:15 UTCEPSS rescore
  21. 2026-07-23 02:03 UTCEG score recompute
  22. 2026-07-22 21:27 UTCEG score recompute▲ 3.60
  23. 2026-07-22 21:27 UTCGHSA enrichment
  24. 2026-07-22 14:06 UTCEPSS rescore
  25. 2026-07-22 14:06 UTCEPSS rescore
Show 40 more
  1. 2026-07-20 17:05 UTCEPSS rescore
  2. 2026-07-13 22:27 UTCEPSS rescore
  3. 2026-07-06 16:25 UTCEPSS rescore
  4. 2026-07-06 02:21 UTCEPSS rescore
  5. 2026-07-05 02:28 UTCEPSS rescore
  6. 2026-07-05 02:28 UTCEPSS rescore
  7. 2026-06-30 23:20 UTCEPSS rescore
  8. 2026-06-30 23:20 UTCEPSS rescore
  9. 2026-06-27 03:06 UTCEPSS rescore
  10. 2026-06-24 14:03 UTCEPSS rescore
  11. 2026-06-24 14:03 UTCEPSS rescore
  12. 2026-06-23 21:31 UTCEPSS rescore
  13. 2026-06-23 21:31 UTCEPSS rescore
  14. 2026-06-22 14:24 UTCEPSS rescore
  15. 2026-06-22 14:24 UTCEPSS rescore
  16. 2026-06-16 17:51 UTCEPSS rescore
  17. 2026-06-16 17:51 UTCEPSS rescore
  18. 2026-06-15 17:46 UTCEPSS rescore
  19. 2026-06-14 23:15 UTCEPSS rescore
  20. 2026-06-13 22:58 UTCEPSS rescore
  21. 2026-06-13 22:58 UTCEPSS rescore
  22. 2026-06-12 23:10 UTCEPSS rescore
  23. 2026-06-12 23:10 UTCEPSS rescore
  24. 2026-06-10 22:16 UTCEPSS rescore
  25. 2026-06-10 13:20 UTCEPSS rescore
  26. 2026-06-06 13:46 UTCEPSS rescore
  27. 2026-06-06 13:46 UTCEPSS rescore
  28. 2026-06-06 13:46 UTCEPSS rescore
  29. 2026-06-05 22:45 UTCEPSS rescore
  30. 2026-06-04 13:10 UTCEPSS rescore
  31. 2026-06-04 13:10 UTCEPSS rescore
  32. 2026-06-01 13:50 UTCEPSS rescore
  33. 2026-06-01 13:50 UTCEPSS rescore
  34. 2026-05-31 00:15 UTCEPSS rescore
  35. 2026-05-31 00:15 UTCEPSS rescore
  36. 2026-05-28 13:43 UTCEPSS rescore
  37. 2026-05-28 13:43 UTCEPSS rescore
  38. 2026-05-26 10:21 UTCEG score recompute
  39. 2026-05-26 10:21 UTCGHSA enrichment
  40. 2026-05-23 12:11 UTCOSV refresh

Publicly available exploits

(1 reference)

Working exploit code is in the public domain. Defenders should treat patch urgency accordingly — public PoCs typically lead to mass-exploitation within 24-72 hours.

  • Nucleihttp/cves/2021/CVE-2021-38156.yaml
    First seen Jan 1, 2021

    Nagios XI < 5.8.6 - Cross-Site Scripting

    Open source ↗

Frequently asked(5)

What is CVE-2021-38156?
CVE-2021-38156 is a critical vulnerability published on September 15, 2021. In Nagios XI before 5.8.6, XSS exists in the dashboard page (/dashboards/#) when administrative users attempt to edit a dashboard.
When was CVE-2021-38156 disclosed?
CVE-2021-38156 was first published in the National Vulnerability Database on September 15, 2021, with the most recent update on November 21, 2024. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2021-38156 actively exploited?
CVE-2021-38156 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 89% probability of exploitation in the next 30 days, which ranks it in the top 0.2% of all scored CVEs.
What is the CVSS score of CVE-2021-38156?
CVE-2021-38156 has a CVSS v3 base score of 5.4 (NVD). EchelonGraph synthesises NVD + CISA KEV + FIRST EPSS + GHSA into a combined EG score of 9.0.
How do I remediate CVE-2021-38156?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2021-38156, 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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