Unvalidated update URL in FearlessCMS enables remote code execution
Key facts
- Attack vector
- Network
- Privileges required
- High
- User interaction
- None
- Attack complexity
- Low
- Impact type
- Code execution
- Confidentiality · integrity · availability
- High · High · High
- Fix status
- Fixed
Attack profile from CVSS 3.1 · CNA. Fix status from CNA. Impact type from CWE-94.
Summary
FearlessCMS versions before 0.1.3b let an authenticated administrator set an arbitrary Git repository URL in the system updater. The updater installs content from that repository without checking its identity, signatures or contents, a code injection flaw (CWE-94). The attacker can run arbitrary PHP with the web server's privileges and keep a backdoor, because existing PHP files under plugins can be executed.
Written with Claude Haiku 5.5 from the sources below · 2026-10-27
Description from the CNA
FearlessCMS is a flat-file content management system centered on simplicity and open source. In 0.1.2b and earlier, an authenticated administrator can set an arbitrary Git repository URL through admin/updater-handler.php and trigger perform_update, which passes the URL to update.sh. The updater clones the repository and replaces the live plugins/, admin/, and includes/ directories without verifying the repository's identity, signatures, or contents. Because router.php permits existing PHP files under plugins to be executed by the PHP development server, attacker-supplied update content can execute arbitrary PHP with the web server process's privileges and persist as a backdoor. This issue is fixed in version 0.1.3b.
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- Poc
- Automatable
- No
- Technical impact
- Total
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| fearlessgeekmedia | FearlessCMS | before 0.1.3b | 0.1.3b | Patch available | CNA |
- FearlessCMS Vendorfearlessgeekmedia Affected before 0.1.3b Fixed in 0.1.3b Patch available CNA
Remediation
Update FearlessCMS to version 0.1.3b, which fixes the issue.
Written with Claude Haiku 5.5 from the sources below · 2026-10-27
- Fix · CNA FearlessCMS (fearlessgeekmedia) Fixed in 0.1.3b
Timeline
- 2026-10-13 Threatist record created from CVE-2026-55695
- 2026-10-13 CISA SSVC decision points changed
- 2026-10-13 Priority changed: MEDIUM → HIGH
References
Other 4
- https://github.com/fearlessgeekmedia/FearlessCMS/security/advisories/GHSA-56wm-3q3v-m93m
- https://github.com/fearlessgeekmedia/FearlessCMS/pull/64
- https://github.com/fearlessgeekmedia/FearlessCMS/commit/6dba91d496463e3940a2c917af3cae97b191de92
- https://github.com/fearlessgeekmedia/FearlessCMS/releases/tag/0.1.3
More fearlessgeekmedia vulnerabilities
- TI-2026-82180 FearlessCMS debug scripts skip login, allowing file access and XSS CVSS 3.1CRITICAL 9.4
- TI-2025-35343 Directory Traversal vulnerability in Fearless Geek Media FearlessCMS v.0.0.2-15 allows a… CVSS 3.1HIGH 7.5
- TI-2025-35342 Directory Traversal vulnerability in Fearless Geek Media FearlessCMS v.0.0.2-15 allows a… CVSS 3.1HIGH 7.5
- TI-2025-35341 Cross Site Scripting vulnerability in Fearless Geek Media FearlessCMS v.0.0.2-15 allows a… CVSS 3.1MEDIUM 6.1
Sources
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences