CVE-2026-55676
Malcolm vulnerable to RCE via unrestricted .php upload to the file-upload component
Malcolm is a network traffic analysis tool suite. The file-upload component (FilePond PHP backend) accepts uploads at POST /server/php/submit.php and stores them in a directory served by the same nginx and php-fpm instance. The allow-list that should restrict accepted file types is an empty array by default (file-upload/php/config.php:16), so the type check is a no-op and every extension is accepted. The filename sanitizer keeps the .php extension intact. Committed files land in /var/www/upload/server/php/files (file-upload/php/config.php:7), and the component's nginx routes any URL ending in .php to php-fpm. An authenticated GET /server/php/files/<name>.php then executes the uploaded code as www-data. Prior to version 26.06.1, in RBAC mode, the upload endpoint is reachable by the granular ROLE_UPLOAD role (nginx/lua/nginx_auth_helpers.lua:71), a role intended only for submitting capture files. As a result, a user holding the upload-only role runs arbitrary PHP as www-data inside the file-upload container. Version 26.06.1 fixes the issue.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- Low
- User interaction
- None
What an attacker can affect
- Confidentiality
- High
- Integrity
- High
- Availability
- High
Exploit likelihood
What each source reports
CVE List Score used
8.7
Malcolm vulnerable to RCE via unrestricted .php upload to the file-upload component
Malcolm is a network traffic analysis tool suite. The file-upload component (FilePond PHP backend) accepts uploads at POST /server/php/submit.php and stores them in a directory served by the same nginx and php-fpm instance. The allow-list that should restrict accepted file types is an empty array by default (file-upload/php/config.php:16), so the type check is a no-op and every extension is accepted. The filename sanitizer keeps the .php extension intact. Committed files land in /var/www/upload/server/php/files (file-upload/php/config.php:7), and the component's nginx routes any URL ending in .php to php-fpm. An authenticated GET /server/php/files/<name>.php then executes the uploaded code as www-data. Prior to version 26.06.1, in RBAC mode, the upload endpoint is reachable by the granular ROLE_UPLOAD role (nginx/lua/nginx_auth_helpers.lua:71), a role intended only for submitting capture files. As a result, a user holding the upload-only role runs arbitrary PHP as www-data inside the file-upload container. Version 26.06.1 fixes the issue.
- Record
CVE-2026-55676- CVSS 4.0
- 8.7 High
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N - CVSS 3.1
- 8.8 High
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H - Weakness
- CWE-434
- Updated
- 2026-11-02
EUVDEUVD-2026-56948
8.7
Malcolm is a network traffic analysis tool suite. The file-upload component (FilePond PHP backend) accepts uploads at POST /server/php/submit.php and stores them in a directory served by the same nginx and php-fpm instance. The allow-list that should restrict accepted file types is an empty array by default (file-upload/php/config.php:16), so the type check is a no-op and every extension is accepted. The filename sanitizer keeps the .php extension intact. Committed files land in /var/www/upload/server/php/files (file-upload/php/config.php:7), and the component's nginx routes any URL ending in .php to php-fpm. An authenticated GET /server/php/files/<name>.php then executes the uploaded code as www-data. Prior to version 26.06.1, in RBAC mode, the upload endpoint is reachable by the granular ROLE_UPLOAD role (nginx/lua/nginx_auth_helpers.lua:71), a role intended only for submitting capture files. As a result, a user holding the upload-only role runs arbitrary PHP as www-data inside the file-upload container. Version 26.06.1 fixes the issue.
- Record
EUVD-2026-56948- CVSS 4.0
- 8.7 High
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N - Updated
- 2026-11-02
NVD
8.7
Malcolm is a network traffic analysis tool suite. The file-upload component (FilePond PHP backend) accepts uploads at POST /server/php/submit.php and stores them in a directory served by the same nginx and php-fpm instance. The allow-list that should restrict accepted file types is an empty array by default (file-upload/php/config.php:16), so the type check is a no-op and every extension is accepted. The filename sanitizer keeps the .php extension intact. Committed files land in /var/www/upload/server/php/files (file-upload/php/config.php:7), and the component's nginx routes any URL ending in .php to php-fpm. An authenticated GET /server/php/files/<name>.php then executes the uploaded code as www-data. Prior to version 26.06.1, in RBAC mode, the upload endpoint is reachable by the granular ROLE_UPLOAD role (nginx/lua/nginx_auth_helpers.lua:71), a role intended only for submitting capture files. As a result, a user holding the upload-only role runs arbitrary PHP as www-data inside the file-upload container. Version 26.06.1 fixes the issue.
- Record
CVE-2026-55676- CVSS 4.0
- 8.7 High
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X - CVSS 3.1
- 8.8 High
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H - Weakness
- CWE-434
- Updated
- 2026-11-02
OSV
8.7
Malcolm vulnerable to RCE via unrestricted .php upload to the file-upload component
Malcolm is a network traffic analysis tool suite. The file-upload component (FilePond PHP backend) accepts uploads at POST /server/php/submit.php and stores them in a directory served by the same nginx and php-fpm instance. The allow-list that should restrict accepted file types is an empty array by default (file-upload/php/config.php:16), so the type check is a no-op and every extension is accepted. The filename sanitizer keeps the .php extension intact. Committed files land in /var/www/upload/server/php/files (file-upload/php/config.php:7), and the component's nginx routes any URL ending in .php to php-fpm. An authenticated GET /server/php/files/<name>.php then executes the uploaded code as www-data. Prior to version 26.06.1, in RBAC mode, the upload endpoint is reachable by the granular ROLE_UPLOAD role (nginx/lua/nginx_auth_helpers.lua:71), a role intended only for submitting capture files. As a result, a user holding the upload-only role runs arbitrary PHP as www-data inside the file-upload container. Version 26.06.1 fixes the issue.
- Record
CVE-2026-55676- CVSS 4.0
- 8.7 High
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N - Weakness
- CWE-434
- Updated
- 2026-11-02
Affected products
History
| Recorded | Changed | Sources |
|---|---|---|
| first indexed | CVE List, EUVD, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2026-55676 is a high vulnerability (CVSS 8.7) in Cisagov Malcolm, published August 11, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.60%, the 49th percentile. No source names a fixed version.
References
github.com/cisagov/Malcolm/security/advisories/GHSA-8cvp-m7pg-qrp7
github.com/cisagov/Malcolm/releases/tag/v26.06.1
cisa.gov/news-events/ics-advisories/icsa-26-230-01
github.com/cisagov/CSAF/blob/develop/csaf_files/OT/white/2026/icsa-26-230-01.json
github.com/CVEProject/cvelistV5/tree/main/cves/2026/55xxx/CVE-2026-55676.json
nvd.nist.gov/vuln/detail/CVE-2026-55676