# CVE-2026-40176: Composer is vulnerable to Command Injection via Malicious Perforce Repository

> Attackers can execute arbitrary commands via malicious Perforce parameters in composer.json, affecting developers running Composer on untrusted projects.

- **Severity:** High 7.8 (`CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 15 Apr 2026
- **Updated:** 15 Jul 2026
- **Also known as:** BIT-composer-2026-40176, DEBIAN-CVE-2026-40176, GHSA-wg36-wvj6-r67p, MINI-468x-f99p-m88f, MINI-7g3q-p72q-4m55, UBUNTU-CVE-2026-40176

## What is CVE-2026-40176?

CVE-2026-40176 is a high-severity command injection vulnerability in composer, published on 15 Apr 2026. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.

### Official description

Composer is a dependency manager for PHP. Versions 1.0 through 2.2.26 and 2.3 through 2.9.5 contain a command injection vulnerability in the Perforce::generateP4Command() method, which constructs shell commands by interpolating user-supplied Perforce connection parameters (port, user, client) without proper escaping. An attacker can inject arbitrary commands through these values in a malicious composer.json declaring a Perforce VCS repository, leading to command execution in the context of the user running Composer, even if Perforce is not installed. VCS repositories are only loaded from the root composer.json or the composer config directory, so this cannot be exploited through composer.json files of packages installed as dependencies. Users are at risk if they run Composer commands on untrusted projects with attacker-supplied composer.json files. This issue has been fixed in Composer 2.2.27 (2.2 LTS) and 2.9.6 (mainline).

Weakness: CWE-78 (Improper Neutralization of Special Elements used in an OS Command), CWE-20 (Improper Input Validation)

## Which versions are affected by CVE-2026-40176?

5 open source packages ship an affected version, including composer/composer and composer. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `composer/composer` | Packagist | From 1.0.0 | 2.2.27 |
| `composer/composer` | Packagist | From 1.0.0 | 2.2.27 |
| `composer/composer` | Packagist | From 2.3.0 | 2.9.6 |
| `composer/composer` | Packagist | From 2.3.0 | 2.9.6 |
| `composer` | Bitnami | From 1.0.0 | 2.2.27, 2.9.6 |

Products: Getcomposer Composer.

## How do I fix CVE-2026-40176?

Upgrade composer/composer to a fixed version for your release line: 2.2.27 or 2.9.6.

## Is CVE-2026-40176 being exploited?

There is no known exploitation of CVE-2026-40176 in the wild and no public exploit code.

Public exploit code:

- https://github.com/Saku0512/CVE-2026-40176-poc (github_poc): https://github.com/Saku0512/CVE-2026-40176-poc
- https://github.com/daptheHuman/cve-2026-40176-cve-2026-40261 (github_poc): https://github.com/daptheHuman/cve-2026-40176-cve-2026-40261
- https://github.com/ikarolaborda/CVE-2026-40176 (github_poc): https://github.com/ikarolaborda/CVE-2026-40176

## Other vulnerabilities in composer

- [CVE-2026-40261](https://insights.sbomify.com/CVE-2026-40261/): Composer has Command Injection via Malicious Perforce Reference (high 8.8)
- [CVE-2024-24821](https://insights.sbomify.com/CVE-2024-24821/): Code execution and possible privilege escalation via compromised InstalledVersions.php or installed.php in Composer (high 8.8)
- [CVE-2015-8371](https://insights.sbomify.com/CVE-2015-8371/): Composer allows cache poisoning from other projects built on the same host (high 8.8)
- [CVE-2021-41116](https://insights.sbomify.com/CVE-2021-41116/): Command injection in composer on Windows (high 8.2)
- [CVE-2025-67746](https://insights.sbomify.com/CVE-2025-67746/): Composer vulnerable to ANSI sequence injection (low 1.3)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-40176 and fix it if it is affected.

What it is: CVE-2026-40176 is a high-severity command injection vulnerability in composer, published on 15 Apr 2026. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2026-40176 in the wild and no public exploit code.

Affected packages and fixed versions:
- composer/composer (Packagist): affected from 1.0.0; fixed in 2.2.27
- composer/composer (Packagist): affected from 1.0.0; fixed in 2.2.27
- composer/composer (Packagist): affected from 2.3.0; fixed in 2.9.6
- composer/composer (Packagist): affected from 2.3.0; fixed in 2.9.6
- composer (Bitnami): affected from 1.0.0; fixed in 2.2.27, 2.9.6

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-2026-40176/ (Markdown: https://insights.sbomify.com/CVE-2026-40176/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-40176
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-40176
- OSV: https://osv.dev/vulnerability/CVE-2026-40176

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-40176/
Summaries are generated and may contain mistakes; the official description above is the record.