CVE-2026-104759: Auth Bypass (CVSS 8.1)

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.

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CVSS v3.1 Score

8.1

HIGH

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS — Exploit Prediction

0.0052

Probability of exploitation

0.43%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-287 Improper Authentication

References

Other 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

Frequently Asked Questions

What is CVE-2026-104759? +

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. It has a CVSS v3.1 base score of 8.1 (HIGH).

How severe is CVE-2026-104759? +

CVE-2026-104759 has a CVSS v3.1 score of 8.1 out of 10, rated HIGH. This is a high-severity vulnerability that should be prioritized for patching. The EPSS score is 0.0052, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-104759? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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