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Fencer Vulns
medium 6.4

CVE-2023-43655 json

Remote Code Execution via web-accessible composer.phar

published 2023-09-29 3 y ago modified 2026-09-08 2 mo ago also BIT-composer-2023-43655 , EUVD-2023-2538 , GHSA-jm6m-4632-36hf

cvss
6.4
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
1.5%
EPSS 1.5% chance of exploitation in 30 days, percentile 74%
public exploits
0
none known

Summary

Composer is a dependency manager for PHP. Users publishing a composer.phar to a public web-accessible server where the composer.phar can be executed as a php file may be subject to a remote code execution vulnerability if PHP also has `register_argc_argv` enabled in php.ini. Versions 2.6.4, 2.2.22 and 1.10.27 patch this vulnerability. Users are advised to upgrade. Users unable to upgrade should make sure `register_argc_argv` is disabled in php.ini, and avoid publishing composer.phar to the web as this is not best practice.

Patch / fix

  • packagist composer/composer 1.10.27, 2.2.22, 2.6.4
  • bitnami composer 1.10.27, 2.2.21, 2.6.4
  • getcomposer composer 1.10.27, 2.2.21, 2.6.4
  • composer Debian 12 2.5.5-1+deb12u4
  • composer Debian 14, Debian 13 2.6.4-1

debian advisories DEBIAN-CVE-2023-43655

  • composer Ubuntu Pro 16.04 LTS 1.0.0~beta2-1ubuntu0.1~esm2
  • composer Ubuntu Pro 18.04 LTS 1.6.3-1ubuntu0.1~esm2
  • composer Ubuntu Pro 20.04 LTS 1.10.1-1ubuntu0.1~esm2
  • composer Ubuntu Pro 22.04 LTS 2.2.6-2ubuntu4+esm1

ubuntu advisories UBUNTU-CVE-2023-43655

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • php-composer2 SLE Module for Web and Scripting 15 SP5, SLE Module for Web and Scripting 15 SP4, openSUSE Leap 15.5 +1 more 2.2.3-150400.3.6.1

suse advisories SUSE-SU-2023:4041-1

  • php-composer2 openSUSE Tumbleweed 2.6.4-1.1

opensuse advisories openSUSE-SU-2024:13290-1

  • composer Alpine 3.24, Alpine 3.23, Alpine 3.22 +4 more 2.6.4-r0

alpine advisories ALPINE-CVE-2023-43655

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2023-43655 updated

composer: Remote Code Execution via web-accessible composer.phar

  • Red Hat All currently supported Red Hat products
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
total
Assessed
2 y ago

Exploit prediction

1.53% chance of exploitation in the next 30 days, higher than 74% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 6.4 CVSS:3.1/AV:N/AC:H/PR:H/UI:R/S:U/C:H/I:H/A:H
GitHub 3.1 8.8 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
NVD 3.1 8.8 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
OSV 3.1 8.8 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Affected packages

ecosystem package affected fixed in
packagist composer/composer
<1.10.27
>=2.0.0, <2.2.22
>=2.3.0, <2.6.4
1.10.27
2.2.22
2.6.4
bitnami composer
<1.10.27
>=2.0.0, <2.2.21
>=2.3.0, <2.6.4
1.10.27
2.2.21
2.6.4

Affected products

  • composer composer
  • docker composer

Classification

Weakness
  • CWE-74 Improper Neutralization of Special Elements in Output Used by a Downstream Component

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.