CVE-2026-39394Public exploitNetwork attack vector

Unauthenticated configuration overwrite via installer newline injection

Published Apr 8, 2026 · Updated Apr 8, 2026

CRLF injection in CI4MS before 0.31.4.0 allows remote attackers to write arbitrary directives to the .env file through the web installer. Install::index passes the unvalidated host POST value to updateEnvSettings, whose preg_replace replacement preserves embedded newlines as new .env entries. The route disables CSRF and becomes reachable on fresh deployments or when the settings cache is empty, enabling URL hijacking, security downgrades, session changes, or service interruption.

CVSS severity8.1
High
EPSS probability0.52%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

CRLF injection in CI4MS before 0.31.4.0 allows remote attackers to write arbitrary directives to the .env file through the web installer. Install::index passes the unvalidated host POST value to updateEnvSettings, whose preg_replace replacement preserves embedded newlines as new .env entries. The route disables CSRF and becomes reachable on fresh deployments or when the settings cache is empty, enabling URL hijacking, security downgrades, session changes, or service interruption.

The record

CVE
CVE-2026-39394
Published
Apr 8, 2026
Updated
Apr 8, 2026
Vendor
Ci4MS
Product
CI4MS
Classifications
CWE-93, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 8, 2026CVE publishedPublication date reported by the CVE source.
  2. Apr 8, 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=< 0.31.4.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Ci4MS · CI4MSversion=< 0.31.4.0

Published CVSS scores

9.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
8.1GitHub, Inc.CVSS:3.1/AV:N/AC:H/PR:N/UI:N/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.

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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 exploitPublished

Weakness, pattern, technique

CWE-93Improper Neutralization of CRLF Sequences ('CRLF Injection')
T1190Exploit Public-Facing Application

Public exploit references

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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