CVE-2026-104803

9.8 CRITICAL

Published 2026-10-10 · Updated 2026-10-13

AI risk analysis

Summary: The WPCOM Member plugin allows unauthenticated attackers to bypass authentication and log in as any user by exploiting missing security checks in the social login callback handler. This vulnerability affects all versions up to 1.7.27 and enables attackers to hijack administrator accounts when the openid or unionid of target users is known.
Exploitability: Exploitation requires knowledge of a victim's bound social provider identifier (openid/unionid) and that the target site has at least one social provider configured, making it moderately difficult but feasible for attackers with basic reconnaissance capabilities.
Blast radius: The vulnerability could lead to full administrative compromise of WordPress sites using the affected plugin, potentially allowing attackers to modify content, install malicious plugins, or exfiltrate sensitive data across multiple user accounts.
Detection: No reliable host or network indicator is derivable from the published description.
Prioritized remediation: Upgrade to version 1.7.28 or later which contains the fix for the authentication bypass vulnerability.

auth-bypasswordpresspluginsocial-login

Analysis generated locally by garnet-coder (no data left the box). AI-assisted — verify against primary sources before acting.

NVD description

The WPCOM Member plugin for WordPress is vulnerable to Authentication Bypass in all versions up to, and including, 1.7.27 via the `uuid` and `code` parameters of the social-login callback handler registered on the `init` hook. The vulnerability exists because the `login` function's social-login flow performs no nonce validation, no OAuth state verification, and no per-visitor namespace isolation in the session store, allowing an unauthenticated attacker to issue a crafted GET request that writes an attacker-named, attacker-valued entry into the global session namespace (bypassing the per-visitor prefix by prepending an underscore), then issue a second GET request triggering `weapp_new_user()` to read that forged entry and resolve the attacker-supplied `openid` value to a bound WordPress account before `wp_set_auth_cookie()` establishes a fully authenticated session. This makes it possible for unauthenticated attackers to log in as any WordPress user — including administrators — whose bound social provider identifier (openid/unionid) is known or discoverable. Successful exploitation requires that the target site has at least one social provider configured (which activates the vulnerable handler) and that the attacker knows or can enumerate the victim account's bound openid or unionid.

CVSS vector

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

Weaknesses

CWE-287

All references

Source data: NVD (nvd.nist.gov), public domain. Exploit-DB.ai adds local AI analysis for defensive use only.

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