vulnerability / NVI-00003302 / Revision 3
baserCMS Path Traversal Leads to Arbitrary File Write and RCE via Theme File API
OSV carries this publisher advisory for baserproject/basercms. This is an aggregated source copy; consult the original publisher and compare update dates.
This report has not inspected your inventory, configuration, deployed build, reachability or evidence. A catalog listing and a severity score do not establish exposure or compromise.
01 / Meaning
Why it matters
Published affected context helps an owner decide what evidence to gather. This report has not examined your application.
7.2 HIGH (3.1)
security-advisories@github.com severity; no combined Null risk score.
1.067%
FIRST EPSS model v2026.06.15; exploitation probability over 30 days, percentile 0.64803. Missing scores are unknown.
As of · FIRST EPSS
02 / Applicability
The affected context
Affected versions, configuration prerequisites and known exclusions are public. Confirm each one against the deployed service.
baserproject/basercms
source listedECOSYSTEM: introduced 0; fixed 5.2.3
## Summary A path traversal vulnerability exists in the baserCMS 5.x theme file management API (`/baser/api/admin/bc-theme-file/theme_files/add.json`) that allows arbitrary file write. An authenticated administrator can include `../` sequences in the `path` parameter to create a PHP file in an arbitrary directory outside the theme directory, which may result in remote code execution (RCE). ## Affected Code **File**: `plugins/bc-theme-file/src/Service/BcThemeFileService.php` ```php public function getFullpath(string $theme, string $plugin, string $type, string $path) { // ... return $viewPath . $type . DS . $path; // $path is not sanitized } ``` ## Attack Scenario 1. The attacker compromises an administrator account (password leak, brute force, etc.) 2. Obtains an access token via API login 3. Specifies `path: "../../../../webroot/"` in the theme file creation API 4. A PHP file is created in the webroot 5. The attacker accesses the created PHP file to achieve RCE ## Reproduction Steps ```bash # 1. Login curl -X POST "http://target/baser/api/admin/baser-core/users/login.json" \ -H "Content-Type: application/json" \ -d '{"email":"admin@example.com","password":"pa
03 / Response
What to do next
- vendor patch
The original advisory lists fixed boundaries 5.2.3 for baserproject/basercms. Confirm the publisher’s latest guidance.
Confirm current vendor support, compatibility and deployment evidence. This report has not tested a fix in your system. GitHub Advisory Database via OSV
- investigate
Identify the exact component and deployed version, examine the linked publisher’s conditions, and retain evidence of any mitigation.
Confirm current vendor support, compatibility and deployment evidence. This report has not tested a fix in your system. FIRST EPSS
A fixed release is not deployment evidence.
Check current vendor support and compatibility. After making a change, verify the deployed build and relevant runtime conditions. Keep the evidence, owner and time. An updated lockfile alone does not prove what is running.
04 / Limits
What this report cannot establish
- Customer inventory, deployment, reachability and exploitation have not been inspected.
- NVD lastModified does not establish freshness of every associated CPE record.
05 / Provenance
Sources you can inspect
Each assertion retains its source. Mirrored records may repeat one underlying publisher; additional links are not independent corroboration.
- GHSA-c5c6-37vq-pjcq ↗
GitHub Advisory Database via OSV · vendor advisory
Observed . GitHub-origin advisory, CC-BY-4.0; OSV is an aggregate copy, not independent corroboration.
- CVE-2026-30940 ↗
NIST National Vulnerability Database · official catalog
Observed . This product uses data from the NVD API but is not endorsed or certified by the NVD.
- CVE-2026-30940 ↗
FIRST EPSS · official catalog
Observed . FIRST EPSS; probability of exploitation in the next 30 days, not local compromise. Dataset date/model retained; FIRST services terms apply.
Public revision history
Only published revisions appear here. Routine fetches do not create a material-change event.
- Revision 3 ·
Source facts changed; compare the preserved prior revision.
- Revision 2 ·
Dated EPSS estimate updated; this is not a new disclosure or proof of exploitation.
- Revision 1 ·
First indexed by Null; source disclosure date is shown separately.