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ComposerApplication · Getcomposer

CVE-2026-40176

HIGH · 7.8 CVSS v3.1 Published 2026-04-15
Fix available
A fix is available. Upgrade to after 2.9.5 or later.
See remediation →
81/100
Remediation priority · High
No privileges

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
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).

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

Composer contains 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 malicious composer.json files declaring a Perforce VCS repository, leading to command execution in the context of the user running Composer, even without Perforce installed.

MitigationUpgrade to Composer 2.2.27 (LTS) or 2.9.6. Avoid running Composer on untrusted projects with attacker-controlled composer.json files that declare Perforce VCS repositories.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
ComposerApplication
Affected:>= 1.0.0, <= 2.2.26>= 2.3.0, <= 2.9.5

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Local
Complexity
Low
Privileges
None
User interaction
Required
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Check installed Composer version
    Run `composer --version` and note the output (for example: Composer version 2.4.0 2022-12-01)
    Affected if The version is >= 1.0.0 and <= 2.2.26, or >= 2.3.0 and <= 2.9.5
  2. Find Perforce VCS repositories
    Search for composer.json files containing `"type": "perforce"` in any repositories section, or inspect the repositories configuration of the project you are running Composer on
    Affected if Any composer.json declares a Perforce VCS repository using the perforce driver
  3. Examine Perforce connection parameters
    Open the composer.json with Perforce repository configuration and inspect the port, user, and client fields under that repository definition
    Affected if These parameters contain unsanitized input that could include shell metacharacters (spaces, semicolons, pipes, command substitution)

You are affected if your Composer version falls within the vulnerable ranges AND you process a composer.json that defines a Perforce VCS repository with attacker-controlled connection parameters.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to a release after 2.9.5
Interim mitigation

Upgrade to Composer 2.2.27 (LTS) or 2.9.6. Avoid running Composer on untrusted projects with attacker-controlled composer.json files that declare Perforce VCS repositories.

Recommended fix High confidence

Composer 2.2.27 (LTS) or Composer 2.9.6 (mainline), depending on which track you are using

  1. Check current Composer version by running: composer --version
  2. If running Composer 2.2.x (LTS), upgrade to version 2.2.27 using: composer self-update 2.2.27
  3. If running Composer 2.3.0 through 2.9.5 (mainline), upgrade to version 2.9.6 using: composer self-update 2.9.6
  4. Alternatively, download the latest Composer from https://getcomposer.org/download/ to ensure you have a fixed version
  5. Verify the upgrade was successful by running composer --version again

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Composer Scoped from the published advisory
  • Consultation2.0 h
  • Implementation2.0 h
  • Testing2.0 h
  • Review / QA1.0 h
7.0 hours of engineering $1,240
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,984.

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-40176 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data