CVE-2026-33508: Parse Server LiveQuery Subscription Query Depth Bypass Vulnerability
Summary
CVE-2026-33508: Parse Server: LiveQuery subscription query depth bypass. Affects parse across 2 version ranges.
< 8.6.56
>= 9.0.0, < 9.6.0
Fixed in 8.6.56 or 9.6.0, depending on the release line you run. How to fix ↓
Also tracked for
- parse-server · npm
The same CVE-2026-33508 is tracked separately for each ecosystem and vendor. Its fix information is the same; the package and affected versions differ.
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Background
Parse Server is an open-source backend platform that allows developers to deploy applications on any infrastructure capable of running Node.js. It provides a robust set of features, including data storage, user authentication, and real-time capabilities through its LiveQuery component. However, prior to versions 8.6.56 and 9.6.0, the LiveQuery component had a significant vulnerability that could be exploited by attackers.
Vulnerability Detail
The vulnerability arises from the lack of enforcement of the requestComplexity.queryDepth configuration setting in Parse Server's LiveQuery component when processing WebSocket subscription requests. This oversight allows an attacker to send a subscription request with deeply nested logical operators, leading to excessive recursion and high CPU consumption. The result can be a degradation of service availability, potentially causing denial-of-service conditions.
How To Fix
Fixed versions by release line
The minimum fixed version depends on the release line you run.
-
< 8.6.568.6.56 -
>= 9.0.0, < 9.6.09.6.0
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Workaround
As a temporary measure, users can limit the complexity of subscription queries by implementing stricter validation on the query depth before processing WebSocket requests. This can be done by adding checks in the server code to reject overly complex queries.
Conclusion
CVE-2026-33508 is a significant vulnerability in the Parse Server's LiveQuery component that can lead to service disruptions. It is crucial for users to update to the latest versions to protect against potential exploitation. Additionally, implementing temporary workarounds can help mitigate risks until an update can be performed.
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FAQ
The impact includes potential denial-of-service conditions due to excessive CPU consumption caused by deeply nested logical operators in subscription requests.
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Versions prior to 8.6.56 and 9.6.0 are affected by this vulnerability.
Yes, updating to version 8.6.56 or later, or 9.6.0 or later, will permanently fix the vulnerability.
If immediate updating is not possible, implement stricter validation on query depth to mitigate the risk temporarily.
References
Related vulnerabilities
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