CVE-2026-16639

CRITICALPre-NVD 9.89.8—
EchelonGraph scoreHIGH confidence

Score 9.8 from GitHub Security Advisory (severity: CRITICAL) published 2026-08-26. CISA-ADP (Vulnrichment) CVSS v3.1 baseline 9.8; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: cisa-adp, epss, ghsa
Trending — 5 sources updated this week
9.8EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 9.8Exploit: None knownExposed: 0

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

Authentication Bypass Using an Alternate Path or Channel vulnerability in Drupal Internationalization Single Sign-On allows Authentication Bypass. This issue affects Internationalization Single Sign-On versions: from 0.0.0 to 1.8.0.

CVSS v3
9.8
EG Score
9.8(high)
EG Risk
59(Track)
EG Risk 59/100SSVC: 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
Severity98% × 45%
Exploitation0% × 40%
Automatability100% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
27%
KEV
Not listed

Published

August 25, 2026

Last Modified

August 28, 2026

Advisory Details (1)

Auto-updated Aug 28, 2026
No patch confirmed yet.
generic

Internationalization Single Sign-On - Critical - Access bypass - SA-CONTRIB-2026-081 | Drupal.org

https://www.drupal.org/sa-contrib-2026-081

Vendor Advisories for CVE-2026-16639(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 36× in last 7d / 36× 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. 2026-08-30 02:56 UTCEG score recompute
  2. 2026-08-30 02:56 UTCGHSA enrichment
  3. 2026-08-30 01:22 UTCEPSS rescore
  4. 2026-08-29 23:07 UTCGHSA enrichment
  5. 2026-08-29 19:19 UTCGHSA enrichment
  6. 2026-08-29 15:28 UTCGHSA enrichment
  7. 2026-08-29 11:39 UTCGHSA enrichment
  8. 2026-08-29 07:47 UTCGHSA enrichment
  9. 2026-08-29 03:57 UTCGHSA enrichment
  10. 2026-08-29 00:02 UTCEG score recompute
  11. 2026-08-29 00:01 UTCGHSA enrichment
  12. 2026-08-28 21:41 UTCEPSS rescore
  13. 2026-08-28 15:49 UTCGHSA enrichment
  14. 2026-08-28 14:18 UTCGHSA enrichment
  15. 2026-08-28 10:27 UTCGHSA enrichment
  16. 2026-08-28 06:36 UTCGHSA enrichment
  17. 2026-08-28 02:46 UTCGHSA enrichment
  18. 2026-08-27 22:57 UTCGHSA enrichment
  19. 2026-08-27 19:07 UTCGHSA enrichment
  20. 2026-08-27 15:18 UTCEG score recompute
  21. 2026-08-27 15:18 UTCGHSA enrichment
  22. 2026-08-27 14:25 UTCEPSS rescore
  23. 2026-08-27 11:29 UTCGHSA enrichment
  24. 2026-08-27 07:40 UTCGHSA enrichment
  25. 2026-08-27 03:50 UTCGHSA enrichment
Show 11 more
  1. 2026-08-27 00:00 UTCGHSA enrichment
  2. 2026-08-26 20:11 UTCEG score recompute
  3. 2026-08-26 20:11 UTCGHSA enrichment
  4. 2026-08-26 16:21 UTCGHSA enrichment
  5. 2026-08-26 15:55 UTCEG score recompute▲ 9.80
  6. 2026-08-26 15:55 UTCGHSA enrichment
  7. 2026-08-26 15:54 UTCMITRE cvelistV5CVSS v3 → 9.8 · severity → CRITICAL
  8. 2026-08-26 14:46 UTCEPSS rescore
  9. 2026-08-25 23:30 UTCNVD update
  10. 2026-08-25 22:35 UTCEG score recompute
  11. 2026-08-25 22:34 UTCMITRE cvelistV5first tracked

Frequently asked(5)

What is CVE-2026-16639?
CVE-2026-16639 is a critical vulnerability published on August 25, 2026. Authentication Bypass Using an Alternate Path or Channel vulnerability in Drupal Internationalization Single Sign-On allows Authentication Bypass. This issue affects Internationalization Single Sign-On versions: from 0.0.0 to 1.8.0.
When was CVE-2026-16639 disclosed?
CVE-2026-16639 was first published in the National Vulnerability Database on August 25, 2026, with the most recent update on August 28, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-16639 actively exploited?
CVE-2026-16639 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 72.7% of all scored CVEs.
What is the CVSS score of CVE-2026-16639?
CVE-2026-16639 has a CVSS v3.1 base score of 9.8 (CISA-ADP / Vulnrichment enrichment; NVD's own analysis pending).
How do I remediate CVE-2026-16639?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-16639, 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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