Parse Server has Regular Expression Denial of Service (ReDoS) via `$regex` query in LiveQuery
Published Mar 9, 2026 · Updated Oct 23, 2026 · Also known as GHSA-mf3j-86qx-cq5j, BIT-parse-2026-30925
Original summary
Normalized public record · Updated Oct 23, 2026
Parse Server has Regular Expression Denial of Service (ReDoS) via `$regex` query in LiveQuery
Publisher and source text is retained separately from QFinch interpretation.
QFinch assessment
A malicious client can subscribe to a LiveQuery with a crafted `$regex` pattern that causes catastrophic backtracking, blocking the Node.js event loop. This makes the entire Parse Server unresponsive, affecting all clients. Any Parse Server deployment with LiveQuery enabled is affected. The attacker only needs the application ID and JavaScript key, both of which are public in client-side apps.
Potential impact
A malicious client can subscribe to a LiveQuery with a crafted $regex pattern that causes catastrophic backtracking, blocking the Node.js event loop. This makes the entire Parse Server unresponsive, affecting all clients. Any Parse Server deployment with LiveQuery enabled is affected. The attacker only needs the application ID and JavaScript key, both of which are public in client-side apps. This only affects LiveQuery subscription matching, which evaluates regex in JavaScript on the Node.js event loop. Normal REST and GraphQL queries are not affected because their regex is evaluated by the database engine.
Evidence: public source recordsAffected products
| Affected package, product or range | Fix status |
|---|---|
| Consult the referenced vendor advisory for affected versions. | Consult source advisory |
Matching a version is only one part of assessing exposure. QFinch has not assessed your environment on this public page.
Remediation
Apply the vendor-supported fixed release or mitigation, then verify the affected component is no longer reachable.
- Confirm the affected product and reachable code path exist in your environment.
- Apply the vendor-supported patch or mitigation from the primary advisory.
- Rescan the exact deployed revision and retain verification evidence.
Evidence coverage
- SSVC priority
- MEDIUM
- Confidence
- 10%
- Aliases
- GHSA-mf3j-86qx-cq5j, BIT-parse-2026-30925
Scores appear only when corresponding evidence exists. Missing data is never interpreted as zero risk.
Sources and record history
Record history
Published Mar 9, 2026 · Last refreshed Oct 23, 2026