CVE-2026-116161 in Parse Server
Summary
by MITRE • 10/25/2026
Parse Server before 8.6.103 and 9.0.0 before 9.10.5-alpha.4 contains an information disclosure vulnerability in LiveQuery. Its subscription hash omits constraints next to a $or operator, including the _Session owner filter and beforeSubscribe constraints, so distinct subscriptions are grouped together. Authenticated clients subscribing with $or queries can receive other users' events, including session tokens usable for impersonation.
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Analysis
by VulDB Data Team • 10/25/2026
The vulnerability identified in Parse Server versions prior to 8.6.103 and 9.0.0 before 9.10.5-alpha.4 represents a critical flaw within the LiveQuery subsystem, specifically concerning how subscription hashes are generated for queries involving logical OR operators. In secure real-time data systems, each user session or query context must be isolated to ensure that events delivered via WebSocket connections correspond strictly to the authorized scope of the requesting client. However, in this affected implementation, the logic responsible for computing the unique identifier for a LiveQuery subscription fails to incorporate specific constraints when they appear alongside a $or operator. This includes critical security filters such as the _Session owner filter, which is designed to restrict data access to only those records owned by the authenticated user, and beforeSubscribe constraints that enforce custom authorization rules defined by the application developer.
By omitting these essential filtering criteria from the subscription hash calculation, the system incorrectly treats distinct subscriptions with different underlying security contexts as identical if their primary query structure appears similar under a logical OR operation. This architectural oversight leads to a scenario where multiple authenticated clients subscribing to data using $or queries are grouped together into a single internal subscription instance. Consequently, when an event occurs that matches any part of the combined query logic, it is broadcasted to all clients associated with that flawed group identifier rather than being filtered and delivered only to those whose specific constraints permit access to that particular piece of information.
The operational impact of this flaw is severe, constituting a significant unauthorized information disclosure vulnerability. Authenticated users can exploit this behavior by crafting malicious subscription requests that leverage the $or operator to inadvertently or intentionally align with other users' active subscriptions. As a result, these attackers receive real-time events intended for other legitimate users. This leakage extends beyond simple data exposure; because LiveQuery often transmits sensitive metadata and identifiers associated with database records, an attacker can capture session tokens belonging to other users. The possession of another user's valid session token allows the attacker to perform full account takeover and impersonation attacks, bypassing authentication mechanisms entirely by assuming the identity of a legitimate victim within the application ecosystem.
From a classification perspective, this vulnerability aligns with CWE-209: Generation of Error Message Containing Sensitive Information in terms of data leakage, though more accurately it falls under CWE-778: Insufficient Initial Alerting for Security Events if viewed through the lens of missing access control enforcement during subscription setup. More critically, it maps directly to CWE-284: Improper Access Control and CWE-359: Exposure of Private Personal Information to an Unauthorized Actor. In terms of offensive security tactics, this flaw facilitates privilege escalation and credential theft, mapping to MITRE ATT&CK techniques such as T1078: Valid Accounts for initial access via stolen tokens and potentially T1530: Data from Cloud Storage Object Discovery if the leaked data includes sensitive file references.
Mitigation requires an immediate upgrade of the Parse Server instance to version 8.6.103 or later, or specifically to version 9.10.5-alpha.4 for those on the newer major branch release candidate track. These updated versions correct the hash generation logic to ensure that all constraints, including session ownership filters and custom beforeSubscribe rules, are fully integrated into the subscription identifier calculation regardless of their position relative to logical operators like $or. Until an upgrade is performed, administrators should consider implementing a reverse proxy or API gateway layer that inspects LiveQuery subscriptions for complex query structures involving OR logic and enforces stricter validation policies at the network edge. Additionally, rotating all active session tokens across the platform is recommended if there is any evidence of exploitation, as existing sessions may have been compromised through this information disclosure channel.