CVE-2026-111699 in wx-api
Summary
by MITRE • 10/16/2026
Niefy wx-api through 0.8.2 contains an authentication bypass vulnerability that allows unauthenticated attackers to impersonate WeChat fans by supplying a raw openid cookie to fan-facing controllers. Attackers knowing a victim's openid can call /wxUser/getUserInfo and /wxUserTags endpoints to read nickname, phone, unionid and tags, and add or remove fan tags.
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Analysis
by VulDB Data Team • 10/16/2026
The vulnerability identified in Niefy wx-api versions through 0.8.2 represents a critical authentication bypass flaw that fundamentally undermines the security model of applications relying on WeChat integration for user identity management. This issue stems from an improper validation mechanism within the framework's fan-facing controllers, which are designed to handle requests originating from users interacting with a WeChat Official Account or Mini Program. The core technical failure lies in the application's acceptance and processing of raw openid values transmitted directly via HTTP cookies without sufficient verification against established session tokens or server-side state. In secure implementations, an openid should be validated through a chain of trust that includes verifying access tokens issued by Tencent’s servers after a user authorizes the application. However, this vulnerability allows any actor who possesses a valid WeChat openid to bypass these checks entirely by simply injecting it into their request cookies, thereby tricking the backend logic into treating them as an authenticated and authorized user associated with that specific identity.
From a technical perspective, the exploitation vector is straightforward yet devastating in its implications for data privacy and integrity. An attacker who has obtained or guessed a victim's openid can send crafted HTTP requests to endpoints such as /wxUser/getUserInfo and /wxUserTags. Because the application fails to enforce strict authentication protocols on these routes, it processes the request using the provided openid cookie as if it were legitimate session state. This allows the attacker to retrieve sensitive personal information including the user's nickname, phone number, unionid, and associated fan tags. Furthermore, the vulnerability extends beyond passive data exfiltration; the application also permits modification of fan attributes through tag management endpoints. Consequently, an adversary can add or remove tags from a victim’s profile without authorization, leading to potential manipulation of marketing campaigns, user segmentation logic, and personalized content delivery systems that rely on accurate tagging for functionality.
The operational impact of this vulnerability is severe, particularly regarding compliance with data protection regulations such as GDPR or China's Personal Information Protection Law (PIPL). The exposure of phone numbers and unique identifiers like unionid constitutes a significant breach of confidentiality, potentially facilitating further social engineering attacks or identity theft against the affected users. Additionally, the ability to alter fan tags introduces risks related to integrity and business logic manipulation. For instance, if an application uses these tags for access control decisions in downstream services or for triggering specific automated workflows, an attacker could manipulate user attributes to bypass additional security layers or disrupt operational processes. This level of unauthorized access erodes trust in the platform and exposes organizations to reputational damage and potential legal liabilities stemming from inadequate protection of personal data.
This flaw aligns with CWE-287, which describes Improper Authentication, specifically where an actor is able to impersonate another user by bypassing authentication mechanisms due to insufficient validation of credentials or session identifiers. In the context of the MITRE ATT&CK framework, this vulnerability facilitates Account Manipulation and Credential Access techniques, as it allows for unauthorized access to existing accounts without needing valid passwords or multi-factor authentication tokens. The attack pattern resembles a form of Session Fixation or IDOR (Insecure Direct Object Reference) depending on how strictly the openid is tied to session state versus being treated as a direct key for data retrieval. To mitigate this risk, developers must implement robust authentication checks that validate requests against server-side sessions rather than trusting client-supplied identifiers alone. It is essential to ensure that all endpoints handling sensitive user data require valid access tokens issued by WeChat’s authorization service and verify these tokens on every request. Additionally, implementing strict input validation and ensuring that cookies are marked with secure flags such as HttpOnly and Secure can help reduce the attack surface. Upgrading to a patched version of Niefy wx-api where this authentication logic has been corrected is the primary remediation step required to restore security posture.