CVE-2023-43655Network attack vector

Remote code execution via query-string arguments

Published Sep 29, 2023 · Updated Jun 18, 2025

Remote code execution in affected Composer releases allows remote attackers to execute code through a web-accessible composer.phar. Under non-CLI PHP SAPIs, Composer consumes query-string-derived argv values when register_argc_argv is enabled instead of refusing PHAR execution. Exploitation requires the PHAR to be published in a web-accessible location, handled as PHP, and invoked with that directive enabled.

CVSS severity6.4
Medium
EPSS probability1.39%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Remote code execution in affected Composer releases allows remote attackers to execute code through a web-accessible composer.phar. Under non-CLI PHP SAPIs, Composer consumes query-string-derived argv values when register_argc_argv is enabled instead of refusing PHAR execution. Exploitation requires the PHAR to be published in a web-accessible location, handled as PHP, and invoked with that directive enabled.

The record

CVE
CVE-2023-43655
Published
Sep 29, 2023
Updated
Jun 18, 2025
Vendor
Composer
Product
Composer
Classifications
T1190, T1059
Attack vector
network
Privileges
admin

Timeline

How it unfolded

  1. Sep 29, 2023CVE publishedPublication date reported by the CVE source.
  2. Jun 18, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 1.10.27
  2. Affected versionversion=>= 2.0, < 2.2.22
  3. Affected versionversion=2.6.4, 2.2.21, 1.10.27

What conditions does exploitation require?

Attack vectornetwork
Required privilegesadmin

What is affected?

Composer · Composerversion=< 1.10.27; version=>= 2.0, < 2.2.22; version=2.6.4, 2.2.21, 1.10.27
Docker · Docker Composeversion=0 <=2.6.4

Published CVSS scores

6.4GitHubCVSS:3.1/AV:N/AC:H/PR:H/UI:R/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesadmin
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1190Exploit Public-Facing Application
T1059Command and Scripting Interpreter

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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