CVE-2026-77694 in Eventin Plugin
Summary
by MITRE • 08/26/2026
The Eventin WordPress plugin before 4.1.19 does not properly restrict which changes a guest checkout token is allowed to authorise on an order, allowing unauthenticated users to mark their own unpaid order as completed and be issued a valid paid ticket with no payment taken.
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Analysis
by VulDB Data Team • 08/26/2026
The vulnerability identified in Eventin versions prior to 4.1.19 represents a critical authentication bypass within the WordPress plugin ecosystem, specifically targeting the guest checkout workflow for event tickets. This flaw stems from an insufficient access control mechanism where the system fails to properly validate whether the entity initiating a state change on an order actually possesses the requisite authorization rights associated with that specific transaction. In typical e-commerce architectures, particularly those involving digital goods like event tickets, there is a strict separation between unauthenticated guest sessions and authenticated user accounts or administrative privileges. The Eventin plugin incorrectly assumes that possession of a generic checkout token grants broad authority over the lifecycle state of an order, rather than restricting actions to only those appropriate for a pending payment scenario.
From a technical perspective, this issue manifests as a Broken Access Control vulnerability where the application logic does not enforce proper ownership verification before processing sensitive status updates. When a user initiates a guest checkout process, they are issued a token intended solely for completing the transaction flow under specific constraints. However, due to the lack of rigorous validation checks on subsequent API calls or AJAX requests, an attacker can manipulate this token to trigger actions that should be reserved for payment gateways or administrative systems. Specifically, the system allows these unauthenticated actors to directly invoke endpoints that transition an order status from pending or unpaid to completed without any corresponding financial transaction occurring in the backend ledger. This effectively decouples the state change of the order from its actual fulfillment conditions, creating a logical flaw that undermines the integrity of the sales process.
The operational impact of this vulnerability is severe for organizations relying on Eventin for ticketing and revenue generation. By exploiting this flaw, an unauthenticated attacker can generate valid entry tickets or access credentials without paying any fees. This leads to direct financial loss through lost revenue from unpaid admissions. Furthermore, it poses significant security risks related to event capacity management and safety compliance. If the vulnerability is exploited at scale, it could lead to overcrowding beyond the venue's legal limits, potentially resulting in liability issues for the event organizers. Additionally, the generation of valid tickets without payment undermines trust in the platform’s integrity, which can have long-term reputational damage for businesses using the software.
This flaw aligns with CWE-269, Improper Privilege Assignment, as it involves granting capabilities to an actor that exceed their intended privileges based on their authentication state. It also maps closely to MITRE ATT&CK technique T1078, Valid Accounts, although in this case, the attacker leverages a validly issued but misused token rather than stolen credentials. The exploitation vector is typically remote and requires no prior authentication, classifying it under CWE-352, Cross-Site Request Forgery (CSRF) if exploited via browser-based attacks, or simply as an Insecure Direct Object Reference (CWE-640) depending on how the token is handled in subsequent requests. The core issue remains a failure to enforce proper authorization checks during state transitions of business-critical objects like orders and tickets.
To mitigate this vulnerability, administrators must immediately update the Eventin WordPress plugin to version 4.1.19 or later, where these access control restrictions have been corrected. Until an upgrade is performed, it is advisable to restrict public access to any custom endpoints associated with order status updates if such functionality exists in a customized implementation. Implementing additional server-side validation that verifies the user’s session state against the expected role for each action can provide a temporary layer of defense. Furthermore, enabling Web Application Firewalls (WAF) rules that monitor for anomalous patterns in checkout token usage may help detect and block exploitation attempts. Regular security audits focusing on authentication and authorization logic are essential to prevent similar flaws from being introduced during future development cycles.