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CVE-2026-104759: WPO365 | SEAMLESS WORDPRESS + MICROSOFT INTEGRATION (WPO365 | LOGIN) <= 44.1 - Unauthenticated Authentication Bypass via OIDC Nonce Replay via id_token Nonce Verification

• Severity: high (CVSS 8.1 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.5% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-10-10 · updated 2026-10-13
• Weakness: CWE-287

Description

The WPO365 | SEAMLESS WORDPRESS + MICROSOFT INTEGRATION (WPO365 | LOGIN) plugin for WordPress is vulnerable to Authentication Bypass via OIDC Nonce Replay in all versions up to, and including, 44.1 This is due to `Id_Token_Service_Deprecated::process_openidconnect_token()` using the incompatible WordPress core `wp_verify_nonce()` function to validate a nonce produced by `Nonce_Service::create_nonce()` — a 64-character hex value that `wp_verify_nonce()` can never successfully verify — causing the nonce check to silently fail without terminating authentication, so execution continues into `authenticate_oidc_user()` with the attacker-supplied `id_token`. This makes it possible for unauthenticated attackers who have obtained a previously-issued, valid `id_token` for a target account to replay that token and authenticate as any WordPress user, including administrators, resulting in full site takeover. This vulnerability is only exploitable when the `use_id_token_parser_v2` plugin option is enabled, as this is the configuration that routes token processing through the deprecated parser containing the broken nonce check.

Affected products

• WPO365 | SEAMLESS WORDPRESS + MICROSOFT INTEGRATION (WPO365 | LOGIN): through 44.1

References

• https://plugins.trac.wordpress.org/browser/wpo365-login/tags/44.1/Services/Id_Token_Service.php#L107
• https://plugins.trac.wordpress.org/browser/wpo365-login/tags/44.1/Services/Id_Token_Service_Deprecated.php#L110
• https://plugins.trac.wordpress.org/browser/wpo365-login/tags/44.1/Services/Nonce_Service.php#L72
• https://plugins.trac.wordpress.org/browser/wpo365-login/tags/44.1/Services/Router_Service.php#L275
• https://plugins.trac.wordpress.org/changeset/3727410/wpo365-login
• https://plugins.trac.wordpress.org/changeset?reponame=&new=3727410%40wpo365-login%2Ftags%2F45.0&old=3682496%40wpo365-login%2Ftags%2F44.1
• https://www.wordfence.com/threat-intel/vulnerabilities/id/aad7ddac-ed12-4263-8e68-64b1fca8dfad?source=cve

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