CVE-2026-84361Network attack vector

Command execution via unvalidated Perforce source address

Published Sep 1, 2026 · Updated Sep 3, 2026

Command injection in Composer 1.0 through 2.2.29 and 2.3.0 through 2.10.2 allows remote attackers to execute local commands via package metadata. Composer\Util\Perforce passes an unvalidated Perforce source.url to p4 as P4PORT, where rsh: and jsh: values instruct the client to spawn a local process. Exploitation requires p4 on PATH, attacker-controlled Perforce source metadata from outside Packagist.org, and a source install; commands run as the user or CI account.

CVSS severity7.7
High
EPSS probability0.41%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Command injection in Composer 1.0 through 2.2.29 and 2.3.0 through 2.10.2 allows remote attackers to execute local commands via package metadata. Composer\Util\Perforce passes an unvalidated Perforce source.url to p4 as P4PORT, where rsh: and jsh: values instruct the client to spawn a local process. Exploitation requires p4 on PATH, attacker-controlled Perforce source metadata from outside Packagist.org, and a source install; commands run as the user or CI account.

The record

CVE
CVE-2026-84361
Published
Sep 1, 2026
Updated
Sep 3, 2026
Vendor
Composer
Product
Composer
Classifications
CWE-78, T1195.001
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Sep 1, 2026CVE publishedPublication date reported by the CVE source.
  2. Sep 3, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

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

  1. Affected versionversion=>= 1.0, < 2.2.30
  2. Affected versionversion=>= 2.3.0, < 2.10.3

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Composer · Composerversion=>= 1.0, < 2.2.30; version=>= 2.3.0, < 2.10.3

Published CVSS scores

7.7GitHubCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

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 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-78Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')
T1195.001Compromise Software Dependencies

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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