Wishlist Member Plugin up to 3.34.1 on WordPress Registration wpm_register/wp_update_user mergewith/wpm_id improper authentication

Summaryinfo

A vulnerability was found in Wishlist Member Plugin up to 3.34.1. It has been declared as critical. Affected by this issue is the function wpm_register/wp_update_user of the component Registration. Executing a manipulation of the argument mergewith/wpm_id can lead to improper authentication. This vulnerability is tracked as CVE-2026-12949. The attack can be launched remotely. No exploit exists.

Detailsinfo

A vulnerability classified as critical was found in Wishlist Member Plugin up to 3.34.1. This vulnerability affects the function wpm_register/wp_update_user of the component Registration. The manipulation of the argument mergewith/wpm_id with an unknown input leads to a improper authentication vulnerability. The CWE definition for the vulnerability is CWE-287. When an actor claims to have a given identity, the product does not prove or insufficiently proves that the claim is correct. As an impact it is known to affect confidentiality, integrity, and availability. CVE summarizes:

The Wishlist Member plugin for WordPress is vulnerable to Account Takeover via Insufficient Verification of Data Authenticity in versions up to and including 3.34.1. This is due to the wpm_register() function validating the registration cookie only against the GET reg parameter while accepting the POST mergewith and POST wpm_id parameters without verifying that the mergewith user ID references a temporary or incomplete registrant that is bound to the current registration transaction. This makes it possible for unauthenticated attackers to take over any existing WordPress account — including administrator accounts — by supplying an arbitrary user's numeric ID as the mergewith value, which causes wp_update_user() to overwrite the target account's username (additionally written via a direct $wpdb UPDATE), password, email address, first name, and last name with attacker-controlled values, while WordPress password and email change notification emails are explicitly suppressed. When wpm_id references a non-existent membership level, no role key is added to the update payload, causing wp_update_user() to preserve the target user's existing role — including administrator — making full privilege escalation a direct consequence of the takeover.

The advisory is available at wordfence.com. This vulnerability was named CVE-2026-12949 since 06/22/2026. The exploitation appears to be easy. The attack can be initiated remotely. No form of authentication is required for a successful exploitation. Technical details are known, but there is no available exploit. The structure of the vulnerability defines a possible price range of USD $0-$5k at the moment (estimation calculated on 08/14/2026).

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

The vulnerability is also documented in the vulnerability database at EUVD (EUVD-2026-58589). If you want to get best quality of vulnerability data, you may have to visit VulDB.

Productinfo

Type

• WordPress Plugin

Name

• Wishlist Member Plugin

Version

• 3.34.0
• 3.34.1

CPE 2.3info

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CPE 2.2info

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If you want to get best quality of vulnerability data, you may have to visit VulDB.

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