CVE-2026-63190: FearlessCMS: Unauthenticated debug scripts expose filesystem operations and XSS

Is it exploited?

Not on CISA's list. CISA has not added it to the Known Exploited Vulnerabilities catalog as of 29 Oct 2026. If CISA adds it, this page shows it as known exploited.

How likely is exploitation in the next 30 days?

0.5%

EPSS score, percentile 45.6 of all scored records. A probability estimated by FIRST, not a report of exploitation.

CISA's SSVC assessment in the CVE record lists exploitation as poc.

How severe?

9.4 Critical

CVSS v3.1 base score, given by the CNA

What should I do?

CISA has set no required action, because the vulnerability is not in KEV.

The CVE record links no vendor advisory, patch or mitigation.

Which versions are affected?

Affected

• < 0.1.4

Versions by product

Source: CISA KEV 2026.10.29, as of 29 Oct 2026; FIRST EPSS, as of 29 Oct 2026; CVE List, as of 30 Oct 2026. About the data.

What to do

Advisories and patches

The CVE record links no vendor advisory, patch or mitigation.

This summary is based on the CVE record as of 30 Oct 2026. Check the vendor's advisory before you act: affected versions and fixes can change.

Affected products and versions

As listed in the CVE record.

Source: CVE List, as of 30 Oct 2026. About the data.

About this vulnerability

FearlessCMS is a flat-file `content` management system centered on simplicity and open source. Prior to version 0.1.4, five debug/test PHP scripts under `admin/` perform privileged operations without `isLoggedIn()` authentication checks, CSRF protection or adequate `path` validation. On PHP's built-in development server, including the default Docker deployment, `router.php` checks an unnormalized…

Summary: CVE record, as of 30 Oct 2026.

• CISA has not added CVE-2026-63190 to its Known Exploited Vulnerabilities (KEV) catalog, as of 29 Oct 2026.
• The CVE record was published on 28 Oct 2026.
• The CVE record carries a CVSS v3.1 base score of 9.4 (Critical), given by its CNA.
• FIRST's EPSS model puts the probability of exploitation in the next 30 days at 0.5% (percentile 45.6), as of 29 Oct 2026. EPSS is a statistical estimate, not a report of exploitation.
• CISA's SSVC assessment in the CVE record: exploitation poc, automatable yes, technical impact total.

Source: CISA KEV 2026.10.29, as of 29 Oct 2026; CVE List, as of 30 Oct 2026; FIRST EPSS, as of 29 Oct 2026. About the data.

Description

FearlessCMS: Unauthenticated debug scripts expose filesystem operations and XSS

FearlessCMS is a flat-file `content` management system centered on simplicity and open source. Prior to version 0.1.4, five debug/test PHP scripts under `admin/` perform privileged operations without `isLoggedIn()` authentication checks, CSRF protection or adequate `path` validation. On PHP's built-in development server, including the default Docker deployment, `router.php` checks an unnormalized admin URI prefix while the filesystem resolves dot segments, so `/./admin/` bypasses the admin login gate and executes those scripts directly. In `admin/debug_save_flow.php`, attacker-controlled `path` and `content` reach `file_put_contents` for arbitrary `.md` writes under `content`/ or outside it through `path` traversal, enabling site defacement and stored JavaScript in public pages; `print_r($_POST)` output without `htmlspecialchars` escaping also causes reflected cross-site scripting. The `admin/debug_content.php` `path` parameter reaches `scandir()`, `file_get_contents()` and `posix_getpwuid()`, permitting arbitrary directory enumeration and `.md` file reads that expose absolute paths, ownership, permissions, hashes and `content` previews. The `admin/preview-handler.php` endpoint accepts JSON `content` and `title` and writes enumerable files under `content/_preview/`, enabling stored cross-site scripting and disk exhaustion. The `admin/testdebug.php` endpoint appends to `admin/testdebug.log` without authentication, also enabling disk exhaustion. The `admin/test_redirect.php` script exposes a test artifact but escapes its inputs and is not itself an XSS sink. Stored script execution can steal sessions and compromise administrators when they view affected `content`. Reads and writes execute with PHP's privileges; the tested deployment runs PHP as root, amplifying filesystem impact. This issue is fixed in version 0.1.4.

Source: CVE List, as of 30 Oct 2026. About the data.

Timeline