CVE-2026-55676
highpriority · track · 0EPSS 0.006 · 49 %ileEUUSEPSS · scored 2026-10-28
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.
remediations
Vendor fix, mitigation, or workaround guidance, as published by each source.
A vendor fix is available.
- FixedMalcolmcisa_csaf_ot
Malcolm version 26.06.1 addresses this issue. For more information, see https://github.com/cisagov/Malcolm/pull/1026. (CVE-2026-55676)
https://github.com/cisagov/Malcolm/pull/1026
cvss
Technical severity, 0–10. One row per scoring source.
base score 0–10 · higher = more severe · hover a vector to decode⚠ sources disagree · medium–high · 6.3–8.8
ssvc
A stakeholder decision — act, attend, or track — from exploitation and impact.
weaknesses
The CWE weakness classes this flaw belongs to.
affected products (3)
Products and version ranges known to be affected.
advisories (1)
Vendor and ecosystem advisories describing this.
- ICSA-26-230-01CISA Malcolm2026-08-18icsa · cisa_csaf_otUS
Successful exploitation of these vulnerabilities could allow an attacker to cause a denial-of-service condition or execute arbitrary code.
also known as (2)
Other names and identifiers for this entity.
sources
Which sources assert this record, and when.
references (8)
External citations — patches, advisories, analysis.
- https://github.com/cisagov/Malcolm/releases/tag/v26.06.1cnnvd
- https://github.com/cisagov/Malcolm/security/advisories/GHSA-8cvp-m7pg-qrp7cnnvd
- https://github.com/cisagov/Malcolm/releases/tag/v26.06.1enisa_euvd
- https://github.com/cisagov/Malcolm/security/advisories/GHSA-8cvp-m7pg-qrp7enisa_euvd
- https://github.com/cisagov/CSAF/blob/develop/csaf_files/OT/white/2026/icsa-26-230-01.jsonnvd
- https://github.com/cisagov/Malcolm/releases/tag/v26.06.1nvd
- https://github.com/cisagov/Malcolm/security/advisories/GHSA-8cvp-m7pg-qrp7nvd
- https://www.cisa.gov/news-events/ics-advisories/icsa-26-230-01nvd
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