Skip to content

CVE-2026-2628 – Microsoft 365 / Azure AD SSO Authentication Bypass in WordPress Plugin

alt text

CVE-2026-2628 Authentication Bypass WordPress Plugin Azure AD SSO

Overview

A critical authentication bypass vulnerability affects the All-in-One Microsoft 365 & Entra ID / Azure AD SSO Login plugin for WordPress (versions <= 2.2.5). The flaw can allow remote attackers to bypass login controls and authenticate as arbitrary WordPress users, including administrators, without valid credentials.

The issue impacts identity federation trust boundaries in plugin-driven SSO flows and can lead to full website compromise where vulnerable versions are deployed.

Technical Specifications

Attribute Details
CVE ID CVE-2026-2628
Vulnerability Type Authentication bypass (CWE-288)
Affected Component All-in-One Microsoft 365 & Entra ID / Azure AD SSO Login plugin (WordPress)
Affected Versions <= 2.2.5
Exploitability Remote, no privileges required, no user interaction
Root Cause Improper validation in SSO login flow accepting malformed auth requests
Authentication Required None
Primary Risk Login as arbitrary user accounts, including admin

Affected Products

  • WordPress sites running vulnerable plugin versions (<= 2.2.5)
  • Environments relying on plugin-based Microsoft 365 / Entra ID SSO integration
  • Sites with publicly reachable authentication endpoints (/wp-login.php and plugin handlers)
  • Administratively exposed WordPress instances with weak segmentation
  • Status: Immediate patching/hardening required

Technical Details

Vulnerability Mechanics

  • Plugin SSO flow does not fully validate parts of inbound authentication data.
  • Certain malformed authentication requests may be treated as valid login assertions.
  • This allows bypass of normal credential and identity verification checks.

Trust Boundary Failure

  • Authentication trust intended for Microsoft identity responses is insufficiently enforced.
  • Improper response validation enables attacker-controlled request manipulation.
  • Exploitation can map directly to privileged WordPress user sessions.

Exposure Conditions

  • Vulnerable plugin version installed and active.
  • WordPress authentication/plugin endpoints reachable by attacker.
  • No user interaction required once crafted request is delivered.

Attack Scenario

  1. Target Identification:

    • Attacker discovers WordPress instance using vulnerable Azure AD/Microsoft 365 SSO plugin.

  2. Payload Crafting:

    • Attacker builds malformed authentication request targeting validation weakness.

  3. Authentication Bypass:

    • Request is accepted by flawed SSO logic without proper identity verification.

  4. Account Impersonation:

    • Attacker gains access as a chosen WordPress account, potentially administrator.

  5. Post-Compromise Actions:

    • Site takeover through plugin/theme modification, malware upload, credential harvesting, and possible lateral movement via server-side footholds.

Impact Assessment

  • Unauthorized login as any WordPress account including administrators
  • Full site modification capability (content, plugin/theme changes, code injection)
  • Persistence via hidden admin accounts or malicious extensions
  • Exposure of user records, configuration data, API keys, and sensitive content
  • Potential theft of credentials and secrets stored on host/application
  • Risk of downstream compromise if shared credentials/integrations exist
  • Service disruption from malicious changes or destructive payload deployment
  • Potential ransomware/web defacement impact on business operations
  • Recovery complexity if attacker establishes persistent backdoors

Mitigation Strategies

Immediate Actions

  • Update plugin to patched version as soon as available
  • If no patch is immediately available, disable the vulnerable SSO plugin

Access Controls

  • Restrict access to /wp-login.php and plugin authentication endpoints via allowlists/VPN/admin network controls
  • Enforce MFA for all WordPress administrator accounts
  • Minimize administrator account count and review role assignments

Monitoring & Detection

  • Monitor logs for unusual login patterns and suspicious admin account changes
  • Alert on unexpected plugin/theme modifications and file integrity drift
  • Investigate authentication events tied to malformed or anomalous SSO request patterns

Resources and References

Open-Source References

Last Updated: March 5, 2026