CVE-2026-40854

HIGHPre-NVD 8.78.7—
EchelonGraph scoreMEDIUM confidence

This high-severity CVE scores 8.7 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.3%, top 77% 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
8.7EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 8.7Exploit: None knownExposed: 0

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

WNC T-Mobile 5G Box IDU router contains an authentication bypass vulnerability in the portal.cgi component. The session verification mechanism improperly validates the sessionid cookie by checking for the existence of a corresponding file in /tmp/login_user. An attacker can bypass authentication by using directory entries such as "." or ".." in the cookie, allowing unauthorized access to the administration panel.This issue has been fixed in firmware version 1.1.0.651412

CVSS v3
8.7
EG Score
8.7(medium)
EG Risk
39(Track)
EG Risk 39/100SSVC: 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
Severity87% × 45%
Exploitation0% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
23%
KEV
Not listed

Published

September 16, 2026

Last Modified

September 16, 2026

Advisory Details (1)

Auto-updated Sep 16, 2026
No patch confirmed yet.
generic

Podatności w routerach WNC T-Mobile 5G Box IDU | CERT Polska

https://cert.pl/posts/2026/09/CVE-2026-40854

Vendor Advisories for CVE-2026-40854(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 / 18× 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. 2026-09-19 14:24 UTCGHSA enrichment
  2. 2026-09-19 03:22 UTCEG score recompute
  3. 2026-09-19 03:22 UTCGHSA enrichment
  4. 2026-09-18 19:28 UTCEPSS rescore
  5. 2026-09-18 16:21 UTCGHSA enrichment
  6. 2026-09-18 05:20 UTCEG score recompute
  7. 2026-09-18 05:20 UTCGHSA enrichment
  8. 2026-09-17 19:31 UTCEPSS rescore
  9. 2026-09-17 18:19 UTCGHSA enrichment
  10. 2026-09-17 06:31 UTCGHSA enrichment
  11. 2026-09-16 19:25 UTCGHSA enrichment
  12. 2026-09-16 18:25 UTCEG score recompute
  13. 2026-09-16 18:25 UTCGHSA enrichment
  14. 2026-09-16 17:45 UTCEG score recompute
  15. 2026-09-16 17:45 UTCGHSA enrichment
  16. 2026-09-16 12:22 UTCEG score recompute
  17. 2026-09-16 11:33 UTCEG score recompute
  18. 2026-09-16 11:30 UTCMITRE cvelistV5first tracked

Frequently asked(5)

What is CVE-2026-40854?
CVE-2026-40854 is a high vulnerability published on September 16, 2026. WNC T-Mobile 5G Box IDU router contains an authentication bypass vulnerability in the portal.cgi component. The session verification mechanism improperly validates the sessionid cookie by checking for the existence of a corresponding file in /tmp/login_user. An attacker can bypass authentication by…
When was CVE-2026-40854 disclosed?
CVE-2026-40854 was first published in the National Vulnerability Database 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-2026-40854 actively exploited?
CVE-2026-40854 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 77.4% of all scored CVEs.
What is the CVSS score of CVE-2026-40854?
CVE-2026-40854 has a CVSS v3 base score of 8.7 (NVD).
How do I remediate CVE-2026-40854?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-40854, 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-2026-40854

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