---
id: "CVE-2026-114655"
kind: "vulnerability"
aliases: ["CVE-2026-114655"]
title: "libmongocrypt: unvalidated key vault values let attackers alter signed KMS requests"
severity: "medium"
cvss: 6.0
epss: 0.00267
exploited: false
status: "open"
category: "package"
products: []
ecosystems: []
tags: ["aws-kms", "azure-kms", "client-side-encryption", "gcp-kms", "libmongocrypt", "mongodb", "package"]
not_affected_if: ["local-kms-provider", "no-untrusted-key-vault-writes"]
published_at: "2026-10-22T19:17:40+00:00"
first_seen_at: "2026-10-23T21:57:31+00:00"
updated_at: "2026-10-25T04:05:23+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-114655", "first_seen_at": "2026-10-23T21:57:31+00:00"}, {"source": "epss", "url": "https://api.first.org/data/v1/epss?cve=CVE-2026-114655", "first_seen_at": "2026-10-24T07:15:51+00:00"}]
---

# libmongocrypt: unvalidated key vault values let attackers alter signed KMS requests

libmongocrypt builds requests to AWS, Azure and GCP key management services by inserting key vault and KMS response values into request lines, headers and signed bodies without encoding them. A user with write access to the key vault collection can change request structure, so the application's credentials sign key operations it did not intend.

_Summary, check and fix written by a model from the sources; labelled as such._

## How to check

- unknown

## Fix

- unknown

## Timeline

- 2026-10-23T21:57:31+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-114655
- 2026-10-24T07:15:51+00:00 epss https://api.first.org/data/v1/epss?cve=CVE-2026-114655

## From the sources

libmongocrypt builds requests to external key management services (AWS, Azure and GCP) by inserting values from key vault documents, KMS provider configuration and KMS responses into request lines, headers and signed request bodies without validating or encoding them for each context. A user with write access to the key vault collection can alter the structure of these requests, including adding members to request bodies and token claims that the library then signs with the application's credentials. This may result in key management operations being performed with parameters the application did not intend.

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_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_