Vulnerability · Published Aug 25, 2026 · Assigned by drupal
CVE-2026-16639Internationalization Single Sign-On - Critical - Access bypass - SA-CONTRIB-2026-081
Critical 9.8
In plain English
A critical-severity authentication bypass in Internationalization Single Sign-On from Drupal. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.6% (higher than 51% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Severity (CVSS 3.1)9.8Critical
Exploit odds (30 days)0.6%top 49.0% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known
Official description
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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Packagist:https://packages.drupal.org/8 | drupal/i18n_sso | 1.8.0 | DRUPAL-CONTRIB-2026-081 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| Drupal | Internationalization Single Sign-On | 0.0.0 – before 1.8.0 |
Weakness: CWE-288 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H