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 — 3 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
28%
KEV
Not listed

Published

August 25, 2026

Last Modified

August 28, 2026

Advisory Details (1)

Auto-updated Sep 18, 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.

Affected Packages

(1 across 1 ecosystem)
Packagist:https://packages.drupal.org/8(1)
PackageVulnerable rangeFixed inDependents
drupal/i18n_sso—1.8.0—

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 54× in last 7d / 196× 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.

Showing the most recent 100 of 196 total refreshes for this CVE.

  1. 2026-09-19 20:27 UTCGHSA enrichment
  2. 2026-09-19 16:38 UTCEG score recompute
  3. 2026-09-19 16:38 UTCGHSA enrichment
  4. 2026-09-19 12:50 UTCGHSA enrichment
  5. 2026-09-19 09:01 UTCGHSA enrichment
  6. 2026-09-19 05:12 UTCGHSA enrichment
  7. 2026-09-19 01:22 UTCGHSA enrichment
  8. 2026-09-18 21:32 UTCEG score recompute
  9. 2026-09-18 21:32 UTCGHSA enrichment
  10. 2026-09-18 19:27 UTCEPSS rescore
  11. 2026-09-18 16:22 UTCGHSA enrichment
  12. 2026-09-18 12:17 UTCGHSA enrichment
  13. 2026-09-18 08:28 UTCGHSA enrichment
  14. 2026-09-18 04:38 UTCGHSA enrichment
  15. 2026-09-18 00:49 UTCGHSA enrichment
  16. 2026-09-17 21:00 UTCEG score recompute
  17. 2026-09-17 21:00 UTCGHSA enrichment
  18. 2026-09-17 14:46 UTCGHSA enrichment
  19. 2026-09-17 10:56 UTCGHSA enrichment
  20. 2026-09-17 07:07 UTCGHSA enrichment
  21. 2026-09-17 03:16 UTCGHSA enrichment
  22. 2026-09-16 23:00 UTCGHSA enrichment
  23. 2026-09-16 19:10 UTCGHSA enrichment
  24. 2026-09-16 14:55 UTCEG score recompute
  25. 2026-09-16 14:55 UTCGHSA enrichment
Show 75 more
  1. 2026-09-16 14:07 UTCEPSS rescore
  2. 2026-09-16 11:06 UTCGHSA enrichment
  3. 2026-09-16 07:16 UTCEG score recompute
  4. 2026-09-16 07:16 UTCGHSA enrichment
  5. 2026-09-16 05:14 UTCEPSS rescore
  6. 2026-09-16 03:25 UTCGHSA enrichment
  7. 2026-09-15 23:34 UTCGHSA enrichment
  8. 2026-09-15 19:25 UTCGHSA enrichment
  9. 2026-09-15 15:36 UTCGHSA enrichment
  10. 2026-09-15 11:47 UTCGHSA enrichment
  11. 2026-09-15 07:58 UTCGHSA enrichment
  12. 2026-09-15 04:08 UTCEG score recompute
  13. 2026-09-15 04:08 UTCGHSA enrichment
  14. 2026-09-15 00:19 UTCGHSA enrichment
  15. 2026-09-14 20:30 UTCGHSA enrichment
  16. 2026-09-14 16:38 UTCGHSA enrichment
  17. 2026-09-14 12:49 UTCGHSA enrichment
  18. 2026-09-14 09:00 UTCGHSA enrichment
  19. 2026-09-14 05:11 UTCGHSA enrichment
  20. 2026-09-14 01:23 UTCGHSA enrichment
  21. 2026-09-13 21:34 UTCGHSA enrichment
  22. 2026-09-13 17:45 UTCEG score recompute
  23. 2026-09-13 17:45 UTCGHSA enrichment
  24. 2026-09-13 16:46 UTCEPSS rescore
  25. 2026-09-13 13:56 UTCGHSA enrichment
  26. 2026-09-13 10:07 UTCGHSA enrichment
  27. 2026-09-13 06:18 UTCGHSA enrichment
  28. 2026-09-13 02:29 UTCGHSA enrichment
  29. 2026-09-12 22:40 UTCGHSA enrichment
  30. 2026-09-12 18:51 UTCGHSA enrichment
  31. 2026-09-12 15:02 UTCEG score recompute
  32. 2026-09-12 15:02 UTCGHSA enrichment
  33. 2026-09-12 15:00 UTCEPSS rescore
  34. 2026-09-12 11:12 UTCGHSA enrichment
  35. 2026-09-12 07:02 UTCGHSA enrichment
  36. 2026-09-12 03:13 UTCGHSA enrichment
  37. 2026-09-11 23:24 UTCGHSA enrichment
  38. 2026-09-11 19:35 UTCGHSA enrichment
  39. 2026-09-11 15:46 UTCEG score recompute
  40. 2026-09-11 15:46 UTCGHSA enrichment
  41. 2026-09-11 14:52 UTCEPSS rescore
  42. 2026-09-11 11:57 UTCEG score recompute
  43. 2026-09-11 11:57 UTCGHSA enrichment
  44. 2026-09-11 09:36 UTCEPSS rescore
  45. 2026-09-11 07:44 UTCGHSA enrichment
  46. 2026-09-11 03:55 UTCGHSA enrichment
  47. 2026-09-11 00:06 UTCGHSA enrichment
  48. 2026-09-10 19:35 UTCGHSA enrichment
  49. 2026-09-10 15:46 UTCGHSA enrichment
  50. 2026-09-10 11:57 UTCEG score recompute
  51. 2026-09-10 11:57 UTCGHSA enrichment
  52. 2026-09-10 09:34 UTCEPSS rescore
  53. 2026-09-10 07:59 UTCGHSA enrichment
  54. 2026-09-10 04:10 UTCGHSA enrichment
  55. 2026-09-10 00:11 UTCGHSA enrichment
  56. 2026-09-09 17:00 UTCGHSA enrichment
  57. 2026-09-09 12:24 UTCGHSA enrichment
  58. 2026-09-09 08:35 UTCGHSA enrichment
  59. 2026-09-09 04:45 UTCGHSA enrichment
  60. 2026-09-09 00:55 UTCEG score recompute
  61. 2026-09-09 00:55 UTCGHSA enrichment
  62. 2026-09-08 22:00 UTCEPSS rescore
  63. 2026-09-08 11:45 UTCGHSA enrichment
  64. 2026-09-08 06:29 UTCGHSA enrichment
  65. 2026-09-08 02:40 UTCGHSA enrichment
  66. 2026-09-07 22:51 UTCGHSA enrichment
  67. 2026-09-07 19:02 UTCEG score recompute
  68. 2026-09-07 19:02 UTCGHSA enrichment
  69. 2026-09-07 16:01 UTCEPSS rescore
  70. 2026-09-07 15:13 UTCGHSA enrichment
  71. 2026-09-07 09:28 UTCGHSA enrichment
  72. 2026-09-07 05:27 UTCGHSA enrichment
  73. 2026-09-07 01:20 UTCGHSA enrichment
  74. 2026-09-06 21:31 UTCGHSA enrichment
  75. 2026-09-06 17:42 UTCGHSA enrichment

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 71.8% 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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