Victim impersonation via insufficient SSO token validation
Published Aug 25, 2026 · Updated Aug 25, 2026
Authentication bypass in Drupal Internationalization Single Sign-On before 1.8.0 allows remote attackers to authenticate as a victim user. The cross-domain login endpoint accepts a short-lived SSO token without sufficient validation before creating the secondary-domain session. Exploitation requires a multilingual site with separate language domains and traffic that appears to originate from the victim's client IP.
Summary
What happened
Authentication bypass in Drupal Internationalization Single Sign-On before 1.8.0 allows remote attackers to authenticate as a victim user. The cross-domain login endpoint accepts a short-lived SSO token without sufficient validation before creating the secondary-domain session. Exploitation requires a multilingual site with separate language domains and traffic that appears to originate from the victim's client IP.
The record
- CVE
- CVE-2026-16639
- Published
- Aug 25, 2026
- Updated
- Aug 25, 2026
- Vendor
- OAuth.js
- Product
- Internationalization Single Sign-On
- Classifications
- CWE-288, CAPEC-115, T1078
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Aug 25, 2026CVE publishedPublication date reported by the CVE source.
- Aug 25, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=0.0.0 <1.8.0
What conditions does exploitation require?
What is affected?
Published CVSS scores
No CVSS assessment is available in this record.
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
No public exploit references are available in this record.
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Technologies
Your stack
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Your stack
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