CVE-2026-84361

## Summary If the `p4` Perforce CLI client is installed, a malicious dependency package from a package repository allowing arbitrary perforce source URLs (packagist.org is safe) could execute arbitrary commands when running `composer install` or `composer update`. Composer passed a package's Perforce source address to the `p4` CLI client without validating it. The `p4` CLI client accepts addresses that mean "run this local command" instead of "connect to this server". This is remote code execution with the privileges of the user or CI account running Composer. ## Am I affected? You are only affected if all of the following are true: - The Perforce `p4` command line client is installed and on the `PATH` of the machine running Composer. - An attacker can control a package metadata's `source` section with a perforce type. Packagist.org does not allow perforce source metadata, so you are only exploitable if you rely on another Composer repository (any custom `composer`-type repository, or an inline `package` repository entry), or a `composer.lock` file you obtained from somewhere you do not trust. - The package gets installed from source, either because it has no dist artifact or because source installs are selected (for example `--prefer-source`). Plainly not affected: anyone without the `p4` client installed, which is the large majority of Composer users. Perforce is an optional VCS integration. Also not affected: projects that only consume packages from Packagist.org, which does not allow Perforce source repositories and therefore cannot serve a package with a Perforce source address. Most realistic way to get hit: a developer workstation or CI image that has Perforce tooling installed, pulling packages from a private or third party Composer repository that an attacker has compromised. ## Patched versions Composer now validates Perforce source addresses before handing them to the `p4` client, and accepts only real network endpoints (an optional `tcp`/`ssl` tr