CVE-2026-88785 in Simple Membership Plugin
Summary
by MITRE • 10/11/2026
The Simple Membership WordPress plugin before 4.8.3 does not avoid transmitting a newly registered member's plaintext password in a URL query string when an optional auto-login-after-registration feature is enabled, exposing the credential in browser history and in web server, proxy, and CDN access logs to anyone able to read them.
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Analysis
by VulDB Data Team • 10/11/2026
The vulnerability identified within versions of the Simple Membership plugin prior to 4.8.3 represents a critical failure in secure credential handling during user registration workflows. Specifically, when the optional auto-login-after-registration feature is enabled, the application constructs a redirect URL that includes the newly registered member's plaintext password as part of the query string parameters. This architectural decision fundamentally violates established security principles regarding the transmission and storage of sensitive authentication data. By embedding credentials directly into the Uniform Resource Identifier, the system inadvertently exposes these secrets to multiple vectors outside the intended secure channel between the client browser and the application server logic that processes the login request.
The operational impact of this flaw is severe due to the widespread logging practices inherent in modern web infrastructure. When a user registers and is automatically logged in via this vulnerable mechanism, their password becomes part of the HTTP GET request sent by the browser. Consequently, this plaintext credential is recorded in multiple locations that are often accessible to system administrators, third-party service providers, or potentially malicious actors with access to log files. These storage points include local web server logs such as those generated by Apache or Nginx, intermediate proxy servers like Varnish or HAProxy, and content delivery network (CDN) edge node logs from services such as Cloudflare or Akamai. Additionally, the password is stored in plaintext within the user's browser history, allowing any individual with physical access to the device or those exploiting cross-site scripting vulnerabilities on other tabs of the same browser session to retrieve the credential.
From a classification perspective, this vulnerability aligns closely with CWE-259, which denotes the use of passwords or keys without proper hashing, and more critically CWE-532, which covers information exposure through log files. The behavior also reflects aspects of CWE-614 regarding sensitive cookies in URLs, although applied to query parameters rather than cookie headers. In terms of adversary tactics as defined by the MITRE ATT&CK framework, this flaw facilitates Credential Access via Browser Reading or Log File Monitoring (T1504). An attacker who gains read access to server logs or CDN archives can harvest these credentials en masse if multiple users utilize the auto-login feature, leading to a widespread compromise of user accounts.
Mitigation strategies must prioritize both immediate remediation and long-term architectural improvements. The most effective solution is to upgrade the Simple Membership plugin to version 4.8.3 or later, where this specific implementation flaw has been addressed by removing the password from the URL query string during the auto-login process. For organizations unable to patch immediately due to compatibility constraints, a temporary workaround involves disabling the auto-login-after-registration feature entirely until an update can be applied. Furthermore, administrators should implement strict log rotation and access control policies to minimize the window of exposure for any credentials that may have already been logged in previous versions. It is also advisable to enforce password resets for all users who registered during periods when this vulnerability was active, as their credentials are likely present in various log archives across the infrastructure stack.