CVE-2026-38991Public exploitNetwork attack vector

Authenticated code execution via filename filter bypass

Published Apr 29, 2026 · Updated Apr 29, 2026

Unrestricted file upload in Cockpit 2.13.5 and earlier allows remote authenticated users to execute arbitrary code through a crafted filename. The Bucket component's _isFileTypeAllowed function accepts a specially crafted name that evades its extension filter, allowing an existing file to be renamed with a .php suffix. A valid Cockpit account and network access to the Bucket workflow are required; execution occurs when the server processes the renamed PHP file.

CVSS severity8.8
High
EPSS probability0.38%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Unrestricted file upload in Cockpit 2.13.5 and earlier allows remote authenticated users to execute arbitrary code through a crafted filename. The Bucket component's _isFileTypeAllowed function accepts a specially crafted name that evades its extension filter, allowing an existing file to be renamed with a .php suffix. A valid Cockpit account and network access to the Bucket workflow are required; execution occurs when the server processes the renamed PHP file.

The record

CVE
CVE-2026-38991
Published
Apr 29, 2026
Updated
Apr 29, 2026
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-434, T1190
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Apr 29, 2026CVE publishedPublication date reported by the CVE source.
  2. Apr 29, 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?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

8.8CISA-ADPCVSS:3.1/AV:N/AC:L/PR:L/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
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-434Unrestricted Upload of File with Dangerous Type
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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