Mongoid ReDoS in Query Evaluation Leads to DoS
CVE-2026-93761 Published on September 18, 2026

Denial of service via unbounded regex matching in Mongoid's in-memory query matcher
An inefficient regular expression complexity issue in the in-memory query evaluation component of the Mongoid library may allow an unauthenticated party to cause excessive processing within an embedding application process. Applications that place user-supplied text into a pattern-matching query condition on an embedded association may become unresponsive.

NVD

Vulnerability Analysis

CVE-2026-93761 can be exploited with network access, and does not require authorization privileges or user interaction. This vulnerability is considered to have a low attack complexity. The potential impact of an exploit of this vulnerability is considered to have no impact on confidentiality and integrity and availability.

Attack Vector:
NETWORK
Attack Complexity:
LOW
Privileges Required:
NONE
User Interaction:
NONE

Weakness Type

What is a ReDoS Vulnerability?

The product uses a regular expression with an inefficient, possibly exponential worst-case computational complexity that consumes excessive CPU cycles. Some regular expression engines have a feature called "backtracking". If the token cannot match, the engine "backtracks" to a position that may result in a different token that can match. Backtracking becomes a weakness if all of these conditions are met:

CVE-2026-93761 has been classified to as a ReDoS vulnerability or weakness.


Affected Versions

MongoDB Inc. Mongoid: