CVE-2026-104893 in Plane
Summary
by MITRE • 10/05/2026
Plane is an open-source project management tool. Prior to 1.4.0, GET /api/users/api-tokens/ allows an authenticated user to retrieve API-token records, while PATCH /api/users/api-tokens/{token_id}/ allows the user to modify the token's allowed_rate_limit field without server-side validation or a maximum value. A user can raise the limit arbitrarily and bypass intended API rate-limiting controls, enabling high-volume automated requests, backend resource abuse, and possible resource exhaustion. This issue is fixed in 1.4.0.
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Analysis
by VulDB Data Team • 10/05/2026
The vulnerability identified within Plane versions prior to 1.4.0 represents a critical failure in server-side input validation regarding API rate limiting configurations. As an open-source project management tool, Plane relies on robust access controls and resource management mechanisms to maintain service availability for its user base. The specific flaw resides in the handling of API token attributes through two distinct endpoints: GET /api/users/api-tokens/ and PATCH /api/users/api-tokens/{token_id}/. While the retrieval endpoint allows authenticated users to view their existing API tokens, the modification endpoint permits changes to the allowed_rate_limit field associated with those tokens without enforcing any upper bounds or validating the integrity of the submitted value against system-defined limits.
From a technical perspective, this issue stems from an improper limit enforcement mechanism where the application accepts arbitrary integer values for rate limiting parameters directly from user input and applies them immediately to the backend configuration. In secure software design, administrative controls such as API throttling should be governed by server-side policies that define maximum permissible thresholds based on subscription tiers or system capacity constraints. By allowing a single authenticated user to unilaterally increase their token's allowed_rate_limit without restriction, Plane effectively disables one of its primary defense-in-depth layers against abuse. This lack of validation allows the application state to diverge significantly from intended operational parameters, creating an exploitable condition where standard security controls are rendered ineffective by configuration manipulation rather than code exploitation in the traditional sense.
The operational impact of this vulnerability is severe and directly affects service availability and resource integrity. An attacker with a valid account can exploit this flaw to escalate their API request quota far beyond normal usage patterns. This capability enables high-volume automated requests that were previously restricted, leading to potential backend resource exhaustion such as CPU saturation, memory depletion, or database connection pool starvation. Such actions constitute a denial-of-service condition against the Plane instance and potentially other tenants if multi-tenancy isolation is not strictly enforced at the infrastructure level. Furthermore, this abuse can lead to increased operational costs for cloud-hosted deployments due to excessive compute usage and may degrade performance for legitimate users sharing the same resources. The ability to bypass rate limiting also facilitates rapid data exfiltration or brute-force attacks against other API endpoints if those endpoints lack independent protection mechanisms.
This vulnerability aligns with CWE-770: Allocation of Resources Without Limits or Throttling, as it involves failing to restrict resource consumption by an actor. It is further categorized under CWE-284: Improper Access Control because the flaw allows a user to modify security-relevant configuration parameters beyond their authorized scope of influence regarding system-wide limits. In terms of MITRE ATT&CK mapping, this behavior corresponds to T1496: Resource Hijacking, where an adversary uses compromised or misconfigured resources for unintended purposes, and potentially T1078: Valid Accounts if the attacker leverages legitimate credentials to perform these unauthorized configuration changes. The exploitation path is straightforward, requiring only authenticated access and a single HTTP PATCH request with a manipulated rate limit value, making it highly accessible to malicious actors who have obtained user credentials through phishing or credential stuffing attacks.
Mitigation strategies must prioritize immediate patching of the Plane instance to version 1.4.0 or later, where this validation logic has been corrected. For organizations unable to upgrade immediately due to dependency constraints, compensating controls should be implemented at the network perimeter level. Web Application Firewalls can be configured to inspect PATCH requests targeting API token endpoints and reject payloads containing rate limit values that exceed predefined thresholds based on historical normal usage or subscription tiers. Additionally, implementing strict input validation rules within any reverse proxy or load balancer layer can provide an additional safeguard against malformed configuration updates. Long-term remediation should involve adopting a security-by-design approach where all administrative configurations are subject to rigorous server-side validation and authorization checks that verify the user's permission level before applying changes to system-wide parameters like rate limits. Regular penetration testing focusing on API endpoint manipulation will help identify similar flaws in other configurable attributes within the application.