CVE-2026-91921

MEDIUMPre-NVD 5.15.1—
EchelonGraph scoreMEDIUM confidence

This medium-severity CVE scores 5.1 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.6%, top 54% 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
Trending — 4 sources updated this week
5.1EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 1%CVSS: 5.1Exploit: None knownExposed: 0

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

Cross-Site Scripting (XSS) vulnerability due to inadequate input sanitisation in the client-side rendering engine of the 1millionbot AI Chat Platform. An unauthenticated remote user could cause external hyperlinks to be rendered in the web interface by sending messages containing Markdown syntax and certain unsanitised content blocks. The impact is limited to the user’s own interactive session; no compromise of internal infrastructure, access to third-party data or impact on administrative panels has been identified.

CVSS v3
5.1
EG Score
5.1(medium)
EG Risk
23(Track)
EG Risk 23/100SSVC: 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
Severity51% × 45%
Exploitation1% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
1%
EPSS %ILE
46%
KEV
Not listed

Published

September 21, 2026

Last Modified

September 22, 2026

Advisory Details (1)

Auto-updated Sep 21, 2026
No patch confirmed yet.
generic

Cross-Site Scripting (XSS) in 1millionbot’s AI chatbot platform | INCIBE-CERT | INCIBE

https://www.incibe.es/en/incibe-cert/notices/aviso/cross-site-scripting-xss-1millionbots-ai-chatbot-platform

Vendor Advisories for CVE-2026-91921(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 14× in last 7d / 14× 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 18:46 UTCEG score recompute
  2. 2026-09-24 18:46 UTCGHSA enrichment
  3. 2026-09-24 14:04 UTCEPSS rescore
  4. 2026-09-23 19:20 UTCEG score recompute
  5. 2026-09-23 19:20 UTCGHSA enrichment
  6. 2026-09-23 17:54 UTCEPSS rescore
  7. 2026-09-22 19:53 UTCEG score recompute
  8. 2026-09-22 19:53 UTCGHSA enrichment
  9. 2026-09-22 16:01 UTCEPSS rescore
  10. 2026-09-22 11:56 UTCGHSA enrichment
  11. 2026-09-21 12:30 UTCEG score recompute
  12. 2026-09-21 11:25 UTCEG score recompute
  13. 2026-09-21 09:50 UTCEG score recompute
  14. 2026-09-21 09:50 UTCMITRE cvelistV5first tracked

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-91921?
CVE-2026-91921 is a medium vulnerability published on September 21, 2026. Cross-Site Scripting (XSS) vulnerability due to inadequate input sanitisation in the client-side rendering engine of the 1millionbot AI Chat Platform. An unauthenticated remote user could cause external hyperlinks to be rendered in the web interface by sending messages containing Markdown syntax…
When was CVE-2026-91921 disclosed?
CVE-2026-91921 was first published in the National Vulnerability Database on September 21, 2026, with the most recent update on September 22, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-91921 actively exploited?
CVE-2026-91921 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 53.9% of all scored CVEs.
What is the CVSS score of CVE-2026-91921?
CVE-2026-91921 has a CVSS v3 base score of 5.1 (NVD).
How do I remediate CVE-2026-91921?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-91921, 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-2026-91921

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