CVE-2026-16639
Internationalization Single Sign-On - Critical - Access bypass - SA-CONTRIB-2026-081
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.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- None
- User interaction
- None
What an attacker can affect
- Confidentiality
- High
- Integrity
- High
- Availability
- High
Exploit likelihood
What each source reports
CVE List Score used
Internationalization Single Sign-On - Critical - Access bypass - SA-CONTRIB-2026-081
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.
- Record
CVE-2026-16639- CVSS 3.1
- 9.8 Critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H - Weakness
- CWE-288
- Updated
- 2026-11-02
EUVDEUVD-2026-66181
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.
- Record
EUVD-2026-66181- CVSS 3.1
- 9.8 Critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H - Updated
- 2026-11-02
GitHub AdvisoriesGHSA-p748-p4j4-gpx6
Authentication Bypass Using an Alternate Path or Channel vulnerability in Drupal...
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.
- Record
GHSA-p748-p4j4-gpx6- CVSS 3.1
- 9.8 Critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H - Weakness
- CWE-288
- Updated
- 2026-11-02
NVD
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.
- Record
CVE-2026-16639- CVSS 3.1
- 9.8 Critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H - Weakness
- CWE-288
- Updated
- 2026-11-02
OSVDRUPAL-CONTRIB-2026-081 No score
In a scenario of a multilingual website with different domain names per language, this module enables you to be automatically connected across the language domains if you are logged on the main language domain.
The module doesn't sufficiently validate a short-lived token, allowing an attacker to bypass access control and authenticate as a victim user.
This vulnerability is mitigated by the fact that an attacker must appear to originate from the same client IP as the victim.
- Record
DRUPAL-CONTRIB-2026-081- Updated
- 2026-11-02
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
drupal/i18n_ssoPackagist:https://packages.drupal.org/8 |
before 1.8.0 | 1.8.0 |
History
| Recorded | Changed | Sources |
|---|---|---|
| first indexed | CVE List, EUVD, GitHub Advisories, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2026-16639 is a critical vulnerability (CVSS 9.8) in Drupal Internationalization Single Sign-on, published July 22, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.64%, the 51st percentile. Fixed in drupal/i18n_sso 1.8.0.