CyberSecBulletin
CVE-2023-43655NVD status: Analyzed

composer: Improper Neutralization of Special Elements in Output Used by a Downstream Component

Published Updated By the CyberSecBulletin desk

CVE-2023-43655 is a high-severity improper neutralization of special elements in output used by a downstream component vulnerability in composer, with a CVSS 3.1 base score of 8.8 out of 10. It can be exploited remotely over the network by an attacker with a low-privileged account, without any action from a user. Affected composer versions: 2.6.4, 2.2.21, 1.10.27; >= 2.0, < 2.2.22; < 1.10.27. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 1.53% chance of exploitation within 30 days, higher than 75% of scored CVEs.

Next patch cycle

High severity with no evidence of exploitation so far.

What to do

  1. Check which version of composer you run against the affected versions below, and install the vendor's latest release.
  2. Read the advisory on github.com for workarounds and exact fixed builds.

Affected products and versions

VendorProductAffected versionsFixed in
Composercomposer2.6.4, 2.2.21, 1.10.27; >= 2.0, < 2.2.22; < 1.10.27Not stated
Dockercomposer2.6.4 and earlierNot stated
DebianDebian Linux10.0Not stated
Fedora ProjectFedora37; 38Not stated

Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.

How the severity score breaks down

Attack vector
NetworkCan be exploited remotely over a network, including the internet.
Attack complexity
LowNo special conditions are needed; the attack works reliably.
Privileges required
LowA basic user account is enough.
User interaction
NoneNo action by a victim is required.
Scope
UnchangedImpact stays within the vulnerable component.
Confidentiality
HighAll data handled by the component can be read.
Integrity
HighData or code can be modified at will.
Availability
HighThe component can be taken down completely.

Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H. Scored by NVD.

Scoring systemScoreSeverityScored by
CVSS 3.16.4MediumCNA (github.com)
CVSS 3.18.8HighNVD

Official description

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.

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: Improper Neutralization of Special Elements in Output Used by a Downstream Component

The product constructs all or part of a command, data structure, or record using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify how it is parsed or interpreted when it is sent to a downstream component.

How developers prevent this class of flaw

  • Programming languages and supporting technologies might be chosen which are not subject to these issues.
  • Utilize an appropriate mix of allowlist and denylist parsing to filter control-plane syntax from all input.

More Improper Neutralization of Special Elements in Output Used by a Downstream Component vulnerabilities (CWE-74)

Timeline

  1. CVE record published.
  2. CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: total).
  3. Record last changed materially (score, affected products, status or references).

References

Other vulnerabilities in composer

All composer vulnerabilities

Recent Improper Neutralization of Special Elements in Output Used by a Downstream Component vulnerabilities

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