CVE-2026-53536 in Activepieces
Summary
by MITRE • 07/16/2026
Activepieces is an open source AI workflow automation platform. Prior to 0.83.0, the /v1/step-files/signed download endpoint verified the supplied JWT against the shared signing secret but did not check the token's audience, and combined with a missing null-check on the decoded fileId, this allowed any caller holding any valid Activepieces JWT (including a freshly created user's own access token) to receive a step-file belonging to another tenant. The file returned was whatever PostgreSQL happened to scan first for type = FLOW_STEP_FILE, varying over time as the database changed, so an authenticated user could obtain step-file attachments belonging to other tenants on the same instance; the attacker could not target a specific victim or file, and the access was read-only with no integrity or availability impact. This issue is fixed in version 0.83.0.
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Analysis
by VulDB Data Team • 07/16/2026
The vulnerability exists within Activepieces, an open source AI workflow automation platform, where a security flaw in the /v1/step-files/signed endpoint permits unauthorized data access between tenants. This issue affects versions prior to 0.83.0 and represents a significant authorization bypass that undermines multi-tenancy security boundaries. The vulnerability stems from insufficient JWT validation practices where the system only verifies the signature against the shared signing secret but fails to validate the token's audience parameter, creating a potential attack vector for cross-tenant data exposure.
The technical implementation flaw involves a missing null-check on the decoded fileId parameter within the endpoint processing logic. This absence allows attackers to manipulate the file retrieval process by supplying valid JWT tokens that belong to other users or tenants. The system's failure to properly validate the token audience combined with inadequate input sanitization creates an exploitable condition where any authenticated user can access step-file attachments belonging to different tenants within the same Activepieces instance. The database query behavior further compounds this issue as PostgreSQL's scanning order for type = FLOW_STEP_FILE entries varies over time, making the returned files unpredictable and dependent on database state rather than specific targeting.
The operational impact of this vulnerability manifests as a read-only data exposure issue that allows attackers to obtain sensitive step-file attachments from other tenants without any integrity or availability compromise. The attacker cannot target specific victims or files due to the unpredictable nature of database scanning, but they can systematically access files belonging to other tenants within the same instance. This represents a violation of data isolation principles and could potentially expose sensitive workflow configurations, automation scripts, or business-critical step definitions that might contain proprietary information or system integration details.
This vulnerability aligns with CWE-284 Access Control Issues, specifically addressing inadequate authorization checks and improper validation of authentication tokens within multi-tenant systems. The flaw also correlates with ATT&CK technique T1566 Privilege Escalation through credential access, where attackers leverage valid credentials to gain unauthorized access to resources belonging to other users or tenants. The missing null-check on the fileId parameter represents a classic input validation failure that enables information disclosure attacks, while the audience validation bypass constitutes a fundamental flaw in the token-based authentication system design.
Mitigation strategies should focus on implementing proper JWT audience validation alongside signature verification to ensure tokens are intended for the specific endpoint being accessed. The system requires a comprehensive null-check mechanism on all decoded parameters before processing file retrieval requests, particularly the fileId parameter that controls which step-file is returned. Database-level access controls and tenant isolation mechanisms should be strengthened to prevent unauthorized cross-tenant data access even when token validation fails. Additionally, implementing proper input sanitization and parameter validation practices will help prevent manipulation of database queries through externally supplied parameters.
The fix implemented in version 0.83.0 addresses the core issue by adding proper audience validation to JWT processing and incorporating null-checks on decoded parameters before file retrieval operations. This update ensures that tokens are validated not only for signature authenticity but also for proper intended audience, preventing unauthorized access to tenant-specific resources. The enhanced validation mechanism prevents attackers from using valid tokens to access resources belonging to other tenants while maintaining the legitimate functionality for authorized users to access their own step-file attachments. Regular security audits and input validation testing should be conducted to prevent similar issues in future releases.
Organizations using Activepieces should immediately upgrade to version 0.83.0 or later to remediate this vulnerability, as it represents a potential exposure of sensitive workflow data across tenant boundaries. The issue highlights the importance of comprehensive authentication validation beyond simple signature checks and demonstrates how seemingly minor implementation flaws can create significant security risks in multi-tenant environments. Continuous monitoring for similar authorization bypass vulnerabilities in token-based systems and proper adherence to security best practices during development will help prevent future occurrences of this class of vulnerability.