Authenticated code execution via unrestricted PHP upload
Published Aug 11, 2026 · Updated Aug 11, 2026
Unrestricted file upload in Malcolm before 26.06.1 allows remote authenticated users to execute arbitrary PHP in the file-upload container. The FilePond PHP backend skips type validation when its allowlist is empty, preserves the .php extension, and stores uploads where nginx sends PHP files to php-fpm. In RBAC mode, an upload-only role can reach both upload and retrieval routes, resulting in code execution as www-data and access to container data and a host-mounted capture directory.
Summary
What happened
Unrestricted file upload in Malcolm before 26.06.1 allows remote authenticated users to execute arbitrary PHP in the file-upload container. The FilePond PHP backend skips type validation when its allowlist is empty, preserves the .php extension, and stores uploads where nginx sends PHP files to php-fpm. In RBAC mode, an upload-only role can reach both upload and retrieval routes, resulting in code execution as www-data and access to container data and a host-mounted capture directory.
The record
- CVE
- CVE-2026-55676
- Published
- Aug 11, 2026
- Updated
- Aug 11, 2026
- Vendor
- Cybersecurity and Infrastructure Security Agency (CISA)
- Product
- Malcolm
- Classifications
- CWE-434, T1505.003
- Attack vector
- network
- Privileges
- authenticated
Timeline
How it unfolded
- Aug 11, 2026CVE publishedPublication date reported by the CVE source.
- Aug 11, 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.
- Affected versionversion=< 26.06.1
What conditions does exploitation require?
What is affected?
Published CVSS scores
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.
Weakness, pattern, technique
Public exploit references
- GHSA-8cvp-m7pg-qrp7 reproductionfunctional · validated
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Technologies
Your stack
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Your stack
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