CVE-2026-100817

MEDIUMPre-NVD 5.45.4—
EchelonGraph scoreHIGH confidence

Score 5.4 from GitHub Security Advisory published 2026-09-29. CISA-ADP (Vulnrichment) CVSS v3.1 baseline 5.4; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: cisa-adp, epss, ghsa
Trending — 5 sources updated this week
5.4EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0.2%CVSS: 5.4Exploit: None knownExposed services: Not assessed

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

Other issue in the JavaScript: WebAssembly component. This vulnerability was fixed in Thunderbird 157 and Firefox 157.

CVSS v3
5.4
EG Score
5.4MEDIUMhigh confidence
EG Risk
24
EG Risk 24/100CISA SSVC

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
Severity54% × 45%
Exploitation0% × 40%
Automatability0% × 15%
CISA SSVC: Track at every mission impact level.
Action: No fix is confirmed yet. Restrict network exposure of the affected system or apply the vendor's mitigation within your standard update timelines, and watch the vendor's advisory for the fix.
EPSS PROB
0.2%
EPSS %ILE
10th
KEV
Not listed

CISA SSVCTrack at every mission impact level.

No fix is confirmed yet. Restrict network exposure of the affected system or apply the vendor's mitigation within your standard update timelines, and watch the vendor's advisory for the fix.

Exploitation none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). Mission impact is CISA's Mission & Well-being decision point, and only you can judge it: high means the affected system is essential to your organisation's mission, or its compromise could cause irreversible harm to people. CISA's decision table

Published

September 29, 2026

Last Modified

October 1, 2026

Advisory Details (3)

Auto-updated Oct 1, 2026
No patch confirmed yet.
generic

Security Vulnerabilities fixed in Firefox 157 — Mozilla

https://www.mozilla.org/security/advisories/mfsa2026-97/
generic

Security Vulnerabilities fixed in Thunderbird 157 — Mozilla

https://www.mozilla.org/security/advisories/mfsa2026-101/
generic

Access Denied

https://bugzilla.mozilla.org/show_bug.cgi?id=2068670

Vendor Advisories for CVE-2026-100817(1)

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

Data Freshness Timeline

(refreshed 22× in last 7d / 22× 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. 2026-10-04 23:21 UTCEPSS rescore
  2. 2026-10-04 17:33 UTCGHSA enrichment
  3. 2026-10-03 17:15 UTCEG score recompute
  4. 2026-10-03 17:15 UTCGHSA enrichment
  5. 2026-10-03 14:25 UTCEPSS rescore
  6. 2026-10-02 16:57 UTCEG score recompute
  7. 2026-10-02 16:57 UTCGHSA enrichment
  8. 2026-10-01 19:49 UTCEPSS rescore
  9. 2026-10-01 16:39 UTCGHSA enrichment
  10. 2026-10-01 15:56 UTCEG score recompute▲ 5.40
  11. 2026-10-01 15:56 UTCGHSA enrichment
  12. 2026-10-01 15:55 UTCMITRE cvelistV5CVSS v3 → 5.4 · severity → MEDIUM
  13. 2026-09-30 18:40 UTCGHSA enrichment
  14. 2026-09-30 18:24 UTCNVD update
  15. 2026-09-30 17:21 UTCEG score recompute
  16. 2026-09-30 17:21 UTCGHSA enrichment
  17. 2026-09-30 17:20 UTCMITRE cvelistV5
  18. 2026-09-30 15:02 UTCEPSS rescore
  19. 2026-09-29 22:02 UTCGHSA enrichment
  20. 2026-09-29 13:35 UTCNVD update
  21. 2026-09-29 12:49 UTCEG score recompute
  22. 2026-09-29 12:48 UTCMITRE cvelistV5first tracked

Frequently asked(5)

What is CVE-2026-100817?
CVE-2026-100817 is a medium vulnerability published on September 29, 2026. Other issue in the JavaScript: WebAssembly component. This vulnerability was fixed in Thunderbird 157 and Firefox 157.
When was CVE-2026-100817 disclosed?
CVE-2026-100817 was first published on September 29, 2026, with the most recent update on October 1, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-100817 actively exploited?
CVE-2026-100817 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.2% probability of exploitation in the next 30 days (10th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-100817?
CVE-2026-100817 has a CVSS v3.1 base score of 5.4 (CISA-ADP / Vulnrichment enrichment; NVD's own analysis pending).
How do I remediate CVE-2026-100817?
No fix for CVE-2026-100817 is confirmed yet. Until one is published, restrict network exposure of the affected system or apply the vendor's mitigation — for example, keep it off the internet or limit it to trusted networks — and watch the vendor's advisory for the fix. The vendor advisories EchelonGraph has for CVE-2026-100817 are linked in the Vendor Advisories panel on this page.

Dependency Blast Radius

Explore the affected products and dependency analysis for CVE-2026-100817

Explore →

Is Your Infrastructure Affected by CVE-2026-100817?

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

Book a Demo →Browse All CVEs