CVE-2026-81900

MEDIUMNVD 6.16.1—
EchelonGraph scoreHIGH confidence

Score 6.1 from GitHub Security Advisory (severity: HIGH) published 2026-09-15. NVD baseline CVSS 6.1; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
Trending — 3 sources updated this week
6.1EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 6.1Exploit: None knownExposed: 0

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

Concrete CMS before 9.5.3 applied only trim() to the YouTube block's stored width and height values and printed them into iframe HTML attributes without escaping or integer casting, resulting in stored cross-site scripting. A user with edit_block permission could inject an event handler that executed script for visitors rendering the page, acting with administrative privileges where the victim was an administrator. The Concrete CMS security team gave this vulnerability a CVSS v4.0 score of 7.3 with vector CVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N. Thanks sh4d0byss for reporting.

CVSS v3
6.1
EG Score
6.1(high)
EG Risk
28(Track)
EG Risk 28/100SSVC: 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
Severity61% × 45%
Exploitation0% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
15%
KEV
Not listed

Published

September 14, 2026

Last Modified

September 16, 2026

References (1)

Vendor Advisories for CVE-2026-81900(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 18× in last 7d / 37× 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. 2026-09-24 15:44 UTCEG score recompute
  2. 2026-09-24 15:44 UTCGHSA enrichment
  3. 2026-09-24 14:04 UTCEPSS rescore
  4. 2026-09-23 17:54 UTCEPSS rescore
  5. 2026-09-23 16:26 UTCGHSA enrichment
  6. 2026-09-22 17:08 UTCEG score recompute
  7. 2026-09-22 17:08 UTCGHSA enrichment
  8. 2026-09-22 16:01 UTCEPSS rescore
  9. 2026-09-21 21:09 UTCEPSS rescore
  10. 2026-09-21 17:37 UTCEG score recompute
  11. 2026-09-21 17:37 UTCGHSA enrichment
  12. 2026-09-20 20:16 UTCEPSS rescore
  13. 2026-09-20 18:17 UTCGHSA enrichment
  14. 2026-09-19 19:00 UTCEG score recompute
  15. 2026-09-19 19:00 UTCGHSA enrichment
  16. 2026-09-18 19:43 UTCEG score recompute
  17. 2026-09-18 19:43 UTCGHSA enrichment
  18. 2026-09-18 19:28 UTCEPSS rescore
  19. 2026-09-17 20:25 UTCEG score recompute
  20. 2026-09-17 20:25 UTCGHSA enrichment
  21. 2026-09-16 21:08 UTCEG score recompute▼ 1.20
  22. 2026-09-16 21:08 UTCGHSA enrichment
  23. 2026-09-16 21:01 UTCNVD updateCVSS v3 → 6.1 · severity → MEDIUM
  24. 2026-09-16 15:09 UTCEG score recompute
  25. 2026-09-16 15:09 UTCGHSA enrichment
Show 12 more
  1. 2026-09-16 14:08 UTCEPSS rescore
  2. 2026-09-16 05:15 UTCEPSS rescore
  3. 2026-09-16 03:01 UTCGHSA enrichment
  4. 2026-09-15 14:53 UTCGHSA enrichment
  5. 2026-09-15 14:34 UTCEG score recompute
  6. 2026-09-15 14:34 UTCGHSA enrichment
  7. 2026-09-15 13:51 UTCEG score recompute
  8. 2026-09-15 13:51 UTCGHSA enrichment
  9. 2026-09-15 11:30 UTCGHSA enrichment
  10. 2026-09-14 23:22 UTCEG score recompute
  11. 2026-09-14 22:24 UTCEG score recompute
  12. 2026-09-14 22:24 UTCMITRE cvelistV5first tracked

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-81900?
CVE-2026-81900 is a medium vulnerability published on September 14, 2026. Concrete CMS before 9.5.3 applied only trim() to the YouTube block's stored width and height values and printed them into iframe HTML attributes without escaping or integer casting, resulting in stored cross-site scripting. A user with edit_block permission could inject an event handler that…
When was CVE-2026-81900 disclosed?
CVE-2026-81900 was first published in the National Vulnerability Database on September 14, 2026, with the most recent update on September 16, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-81900 actively exploited?
CVE-2026-81900 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 84.7% of all scored CVEs.
What is the CVSS score of CVE-2026-81900?
CVE-2026-81900 has a CVSS v3 base score of 6.1 (NVD).
How do I remediate CVE-2026-81900?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-81900, 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-2026-81900

Explore →

Is Your Infrastructure Affected by CVE-2026-81900?

EchelonGraph automatically scans your cloud infrastructure and maps CVE exposure using blast radius analysis.

Book a Demo →Browse All CVEs