# CVE-2026-106433: MongoDB libmongocrypt state management memory corruption

Source: https://junglewise.ai/threats/cve-2026-106433-improper-state-management-in-mongodb-libmongocrypt-can-cause  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-10-08. Updated: 2026-10-27  
License: CC BY 4.0 with a link back

CVE-2026-106433 · Severity: high · CVSS 8.8 · Published 2026-10-08

MongoDB libmongocrypt, a library used for client-side encryption in database applications, contains a flaw in how it manages encryption key data. When a key vault document contains duplicate masterKey fields, the library may misinterpret the data type during cleanup, leading to invalid memory access and data corruption that can crash the application or corrupt its memory.

Technologies: [MongoDB Libmongocrypt](https://junglewise.ai/threats/technologies/libmongocrypt). Vendors: [MongoDB](https://junglewise.ai/threats/vendors/mongodb).

## Quick answers

**Is CVE-2026-106433 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-106433 being exploited in the wild.

**How severe is CVE-2026-106433?** High severity, with a CVSS score of 8.8, published 8 October 2026.

**Which products and versions are affected?** MongoDB Libmongocrypt before 1.20.5.

**Is there a fix for CVE-2026-106433?** Yes: fixed in libmongocrypt 1.20.5. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-106433 attacked?** It is attacked over the network.

**Am I affected by CVE-2026-106433?** Check whether you run MongoDB Libmongocrypt at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- Fixed in libmongocrypt 1.20.5

## Technical details

The vulnerability is an improper state management flaw in libmongocrypt's key document cleanup logic that occurs when a key vault document contains duplicate masterKey fields. An authenticated actor with the ability to modify key vault documents, or a malicious server returning such documents, can trigger invalid memory access and invalid free operations. This results in denial of service through application termination or potential memory corruption within the client process.

## Affected products

- MongoDB libmongocrypt before 1.20.5

## Timeline

- 2026-10-08: disclosed: CVE-2026-106433 published

## References

- [https://jira.mongodb.org/browse/MONGOCRYPT-964](https://jira.mongodb.org/browse/MONGOCRYPT-964)

## Related threats

- [libmongocrypt out-of-bounds write in key-management request builder](https://junglewise.ai/threats/cve-2026-126792-a-memory-safety-flaw-in-the-key-management-request-building)
- [libmongocrypt KMS request injection in key vault processing](https://junglewise.ai/threats/cve-2026-114655-libmongocrypt-builds-requests-to-external-key-management)
- [MongoDB Crypt key vault privilege escalation to Google Cloud KMS](https://junglewise.ai/threats/cve-2026-84962-mongodb-crypt-key-vault-privilege-escalation-to-google-cloud-kms)
- [MongoDB libmongocrypt denial of service via undersized encrypted payload](https://junglewise.ai/threats/cve-2026-84971-mongodb-libmongocrypt-denial-of-service-via-undersized-encrypted)
- [MongoDB libmongocrypt input validation bypass in automatic encryption](https://junglewise.ai/threats/cve-2026-81523-mongodb-libmongocrypt-input-validation-bypass-in-automatic)