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CVE-2021-29472

29
FAUCET Score

CVE-2021-29472 is a critical vulnerability in Composer, a PHP dependency manager, affecting versions 1.10.22 and 2.0.13 and earlier. It allows remote code execution (RCE) due to improper sanitization of Mercurial repository URLs in composer.json files and package source download URLs, impacting services like Packagist.org. With a CVSS score of 8.8 (HIGH), it presents a significant risk (FAUCET Risk Score 75/100) as an unauthenticated attacker could achieve full compromise (C:H, I:H, A:H) with low attack complexity. Although patched on Packagist.org and Private Packagist and not observed to be actively exploited, the vulnerability has garnered community attention, including a Reddit discussion and media coverage, indicating its potential for future exploitation. No public exploit code or Metasploit modules are currently available.

Impacted Technologies

VendorProductVersion(s)CPE
< 1.10.22CPE matchmatch criteria
cpe:2.3:a:getcomposer:composer:*:*:*:*:*:*:*:*
>= 2.0, < 2.0.13CPE matchmatch criteria
cpe:2.3:a:getcomposer:composer:*:*:*:*:*:*:*:*
9.0CPE matchmatch criteria
cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*
10.0CPE matchmatch criteria
cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:*
33CPE matchmatch criteria
cpe:2.3:o:fedoraproject:fedora:33:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

8.8HIGH

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

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
Exploitability Score
2.8
Impact Score
5.9
CvssVersion
3.1

Exploit Intelligence

EPSS Score
4.66%
Probability of exploitation in next 30 days
EPSS Percentile
90.8%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0466 is in the 90th percentile among its peer group of 17,823 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.3 Bluesky, 0.1 Mastodon, and 0.2 GitHub mentions.

Media Mentions

The average CVE in this peer group has 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (2)

composerpatch availablevia ghsa
Product: composer/composerFixed in: 1.10.22
composerpatch availablevia ghsa
Product: composer/composerFixed in: 2.0.13

Vendor Advisories (1)

composerGHSA-h5h8-pc6h-jvvxhigh

Composer's missing argument delimiter can lead to code execution via VCS repository URLs or source download URLs on systems with Mercurial

Apr 29, 2021

References

blog.sonarsource.com / php-supply-chain-attack-on-composer
ExploitThird Party Advisory
getcomposer.org
Vendor Advisory
github.com / composer/composer/security/advisories/GHSA-h5h8-pc6h-jvvx
Third Party Advisory
lists.debian.org / debian-lts-announce/2021/05/msg00009.html
Mailing ListThird Party Advisory
lists.fedoraproject.org / archives/list/package-announce%40lists.fedoraproject.org/message/FAQUAMGO4Q4BLNZ2OH4CXQD7UK4IO2GE
lists.fedoraproject.org / archives/list/package-announce%40lists.fedoraproject.org/message/KN3DMFH42BJW45VT6FYF2RXKC26D6VC2
debian.org / security/2021/dsa-4907
Third Party Advisory