# CVE-2026-93761: Denial of service via unbounded regex matching in Mongoid's in-memory query matcher

> An attacker can cause denial of service in applications using Mongoid by supplying input that triggers excessive regex processing.

- **Severity:** High 8.7 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 18 Sep 2026
- **Updated:** 19 Sep 2026
- **Also known as:** GHSA-6c34-f5wx-m58m

## What is CVE-2026-93761?

CVE-2026-93761 is a high-severity denial of service vulnerability in MongoDB Inc. Mongoid, published on 18 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

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.

Weakness: CWE-1333 (Inefficient Regular Expression Complexity)

## Which versions are affected by CVE-2026-93761?

It affects 1 product.


Products: Mongodb Mongoid.

## How do I fix CVE-2026-93761?

No fix has been published for CVE-2026-93761 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-93761 being exploited?

There is no known exploitation of CVE-2026-93761 in the wild and no public exploit code.

## Other vulnerabilities in MongoDB Inc. Mongoid

- [CVE-2026-93762](https://insights.sbomify.com/CVE-2026-93762/): Data deletion and attribute disclosure via field-name method injection in in-memory queries (critical 9.2)
- [CVE-2026-93759](https://insights.sbomify.com/CVE-2026-93759/): Server-side JavaScript injection via string query criteria bypassing the strict operator allowlist (high 8.8)
- [CVE-2026-93758](https://insights.sbomify.com/CVE-2026-93758/): Cross-principal document update, theft, and deletion via unvalidated id in nested attributes (high 8.6)
- [CVE-2026-93760](https://insights.sbomify.com/CVE-2026-93760/): NoSQL injection of JavaScript-executing query operators via unsafe-by-default operator guard (high 8.3)
- [CVE-2026-93765](https://insights.sbomify.com/CVE-2026-93765/): Document deletion and process crash via unvalidated method-name dispatch in atomic pop operation (high 8.3)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-93761 and fix it if it is affected.

What it is: CVE-2026-93761 is a high-severity denial of service vulnerability in MongoDB Inc. Mongoid, published on 18 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-93761 in the wild and no public exploit code.

Affected product: MongoDB Inc. Mongoid. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-93761/ (Markdown: https://insights.sbomify.com/CVE-2026-93761/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-93761
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-93761
- OSV: https://osv.dev/vulnerability/CVE-2026-93761

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From sbomify Insights: https://insights.sbomify.com/CVE-2026-93761/
Summaries are generated and may contain mistakes; the official description above is the record.