# CVE-2026-81525: Cross-tenant database retargeting via dot/NUL injection in namespace strings in the PHP Driver

> Attackers can redirect database operations to unintended namespaces via injection in PHP driver namespace strings, risking cross-tenant data access.

- **Severity:** High 8.6 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/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:** CLSA-2026-1790259386, DEBIAN-CVE-2026-81525, GHSA-65fr-j4p9-vc33, UBUNTU-CVE-2026-81525

## What is CVE-2026-81525?

CVE-2026-81525 is a high-severity vulnerability in MongoDB PHP Extension, published on 27 Aug 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

The MongoDB client library for PHP does not sufficiently sanitize special elements in application-supplied namespace identifiers before using them to construct the target namespace for database operations. An application that incorporates untrusted text into these identifiers may have operations silently directed at a different storage location than the one the application intended.

Weakness: CWE-943 (Improper Neutralization of Special Elements in Data Query Logic)

## Which versions are affected by CVE-2026-81525?

4 open source packages ship an affected version, including mongodb/mongodb. It affects 2 products.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `mongodb/mongodb` | Packagist | All versions | 1.21.4 |
| `mongodb/mongodb` | Packagist | All versions | 1.21.4 |
| `mongodb/mongodb` | Packagist | From 2.0.0 | 2.4.1 |
| `mongodb/mongodb` | Packagist | From 2.0.0 | 2.4.1 |

Products: Mongodb Php Driver, Mongodb Php Library.

## How do I fix CVE-2026-81525?

Upgrade mongodb/mongodb to a fixed version for your release line: 1.21.4 or 2.4.1.

## Is CVE-2026-81525 being exploited?

There is no known exploitation of CVE-2026-81525 in the wild and no public exploit code.

## Other vulnerabilities in MongoDB PHP Extension

- [CVE-2026-84968](https://insights.sbomify.com/CVE-2026-84968/): Heap out-of-bounds read via corrupt nested BSON in field path error message (medium 6.9)
- [CVE-2026-106436](https://insights.sbomify.com/CVE-2026-106436/): Application denial of service and data truncation via unchecked BSON append failures in MongoDB PHP Driver (medium 6.3)
- [CVE-2026-6811](https://insights.sbomify.com/CVE-2026-6811/): PHP Stack Exhaustion (medium 6.0)
- [CVE-2026-106432](https://insights.sbomify.com/CVE-2026-106432/): Heap buffer overflow via 32-bit string-length truncation in MongoDB PHP Driver (low 2.0)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-81525 and fix it if it is affected.

What it is: CVE-2026-81525 is a high-severity vulnerability in MongoDB PHP Extension, 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-2026-81525 in the wild and no public exploit code.

Affected packages and fixed versions:
- mongodb/mongodb (Packagist): affected all versions; fixed in 1.21.4
- mongodb/mongodb (Packagist): affected all versions; fixed in 1.21.4
- mongodb/mongodb (Packagist): affected from 2.0.0; fixed in 2.4.1
- mongodb/mongodb (Packagist): affected from 2.0.0; fixed in 2.4.1

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-2026-81525/ (Markdown: https://insights.sbomify.com/CVE-2026-81525/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-81525
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-81525
- OSV: https://osv.dev/vulnerability/CVE-2026-81525

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-81525/
Summaries are generated and may contain mistakes; the official description above is the record.