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

> Attackers can redirect database operations to unintended resources via unsanitized namespace strings, risking unauthorized data access or modification.

- **Severity:** Medium 5.3 (`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`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 27 Aug 2026
- **Updated:** 28 Aug 2026
- **Also known as:** DEBIAN-CVE-2026-81524, UBUNTU-CVE-2026-81524, openSUSE-SU-2026:11671-1

## What is CVE-2026-81524?

CVE-2026-81524 is a medium-severity vulnerability in MongoDB C Driver, published on 27 Aug 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official 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.

Weakness: CWE-99 (Improper Control of Resource Identifiers)

## Which versions are affected by CVE-2026-81524?

It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `mongo-c-driver` | openSUSE:Tumbleweed | All versions | 2.5.1-1.1 |

Products: Mongodb C Driver.

## How do I fix CVE-2026-81524?

Apply the vendor's patch.

## Is CVE-2026-81524 being exploited?

There is no known exploitation of CVE-2026-81524 in the wild and no public exploit code.

## Other vulnerabilities in MongoDB C Driver

- [CVE-2026-93393](https://insights.sbomify.com/CVE-2026-93393/): Heap overflow via oversized decrypted TLS record sequence in Windows Secure Channel stream (critical 9.2)
- [CVE-2026-6691](https://insights.sbomify.com/CVE-2026-6691/): MongoDB C Driver Cyrus SASL Canonicalization Buffer Overflow (high 8.6)
- [CVE-2026-84964](https://insights.sbomify.com/CVE-2026-84964/): Heap corruption via OCSP request double free from crafted multi-URL certificate in TLS client (high 8.2)
- [CVE-2024-7553](https://insights.sbomify.com/CVE-2024-7553/): Accessing Untrusted Directory May Allow Local Privilege Escalation (high 7.3)
- [CVE-2026-93395](https://insights.sbomify.com/CVE-2026-93395/): Integer Underflow → Heap Out-of-Bounds Read in `bson_new_from_buffer() (medium 6.9)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-81524 and fix it if it is affected.

What it is: CVE-2026-81524 is a medium-severity vulnerability in MongoDB C Driver, published on 27 Aug 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-81524 in the wild and no public exploit code.

Affected product: MongoDB C Driver. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-81524/ (Markdown: https://insights.sbomify.com/CVE-2026-81524/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-81524
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-81524
- OSV: https://osv.dev/vulnerability/CVE-2026-81524

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-81524/
Summaries are generated and may contain mistakes; the official description above is the record.