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Parse Server LiveQuery subscription with invalid regular expression crashes server

Moderate severity GitHub Reviewed Published Mar 16, 2026 in parse-community/parse-server

Package

npm parse-server (npm)

Affected versions

>= 9.0.0, < 9.6.0-alpha.19
< 8.6.43

Patched versions

9.6.0-alpha.19
8.6.43

Description

Impact

A remote attacker can crash the Parse Server by subscribing to a LiveQuery with an invalid regular expression pattern. The server process terminates when the invalid pattern reaches the regex engine during subscription matching, causing denial of service for all connected clients.

Patches

The fix validates regular expression patterns at subscription time, rejecting invalid patterns before they are stored. Additionally, a defense-in-depth try-catch prevents any subscription matching error from crashing the server process.

Workarounds

Disable LiveQuery if it is not needed.

References

@mtrezza mtrezza published to parse-community/parse-server Mar 16, 2026
Published to the GitHub Advisory Database Mar 17, 2026
Reviewed Mar 17, 2026

Severity

Moderate

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
High
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS score

Weaknesses

Uncaught Exception

An exception is thrown from a function, but it is not caught. Learn more on MITRE.

CVE ID

CVE-2026-32770

GHSA ID

GHSA-827p-g5x5-h86c

Source code

Credits

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