CVE-2026-30932 in Froxlor
Summary
by MITRE • 03/24/2026
Froxlor is open source server administration software. Prior to version 2.3.5, 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. This issue has been patched in version 2.3.5.
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Analysis
by VulDB Data Team • 06/05/2026
The vulnerability identified as CVE-2026-30932 affects Froxlor, an open source server administration software package that provides web hosting management capabilities including DNS zone management. This issue represents a significant security flaw in the software's API implementation that could potentially allow attackers to manipulate DNS zone files through the DomainZones.add endpoint. The vulnerability specifically impacts customers who have DNS functionality enabled within their Froxlor installation, creating a potential attack vector that could compromise the integrity of DNS records and potentially lead to broader system compromise.
The technical flaw resides in the insufficient validation of the content field within the DomainZones.add API endpoint. This endpoint is designed to be accessible to customers with DNS capabilities, but the implementation fails to properly sanitize input for several specific DNS record types including LOC (Location), RP (Responsible Person), SSHFP (SSH Fingerprint), and TLSA (Transport Layer Security Authentication) records. The lack of proper input validation allows malicious actors to inject newline characters and BIND zone file directives such as $INCLUDE into the content field. This injection occurs because the software does not adequately filter or escape special characters that could be interpreted as zone file directives by the DNS server software.
The operational impact of this vulnerability is substantial and multifaceted. When attackers successfully exploit this flaw, they can inject arbitrary BIND zone file directives into the zone files that are written to disk during the DNS rebuild cron job execution. The $INCLUDE directive is particularly dangerous as it allows attackers to reference external files that could contain malicious content, potentially leading to remote code execution or data exfiltration. The vulnerability essentially creates a path for attackers to modify the DNS zone configuration files in ways that could redirect traffic, compromise services, or provide unauthorized access to system resources. This type of vulnerability aligns with CWE-113 (Improper Neutralization of CRLF Sequences) and CWE-94 (Improper Control of Generation of Code) as it involves improper handling of control characters and code generation through user input.
The attack surface is particularly concerning given that the vulnerability affects the DNS rebuild process which is typically automated and runs periodically. This means that any successful injection could persist until the next DNS rebuild cycle, potentially providing attackers with extended access windows. The vulnerability also demonstrates a failure in the principle of least privilege, as customer-facing API endpoints should not be allowed to directly influence system-level configuration files. This issue can be mapped to ATT&CK technique T1059.007 (Command and Scripting Interpreter: Python) and T1566.001 (Phishing: Spearphishing Attachment) as attackers might use this vulnerability to establish persistent access through injected zone files that could contain malicious DNS records or redirect traffic to compromised systems.
Mitigation strategies should focus on immediate patch application to version 2.3.5 which contains the necessary fixes for this vulnerability. Organizations should also implement additional monitoring of DNS zone file changes to detect any unauthorized modifications that might occur due to this vulnerability. The fix should include comprehensive input validation that properly sanitizes all user-provided content fields, particularly for DNS record types that are known to be susceptible to injection attacks. Additionally, system administrators should review and restrict access to DNS management features where possible, implementing proper access controls and input filtering mechanisms. The vulnerability highlights the importance of validating and sanitizing all user input in API endpoints that interact with system-level configuration files, a principle that should be reinforced in all software development practices to prevent similar issues in the future.