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GHSA-5rw4-4665-cvwf
froxlor/froxlorFroxlor's DomainZones.add API command accepts user-controlled DNS record and type values and later writes them into generated BIND zone files without rejecting line delimiters, tab characters, or zone-file comment delimiters.
The stronger variant is in record. An authenticated customer with DNS-zone permissions can submit a normal A record request where record is:
www\t60\tIN\tA\t6.6.6.6 ;\n@
with type=A and content=127.0.0.1. The current record flow trims/lower-cases/IDNA-encodes the value, but does not reject CR/LF/HTAB or semicolon. The real Froxlor\Dns\DnsEntry::__toString() sink renders it as:
www 60 in a 6.6.6.6 ; @ 18000 IN A 127.0.0.1
BIND accepts the generated zone file:
named-checkzone example.com froxlor_dns_record_injected.zone zone example.com/IN: loaded serial 2026060501 OK
named-compilezone -D confirms both records are parsed as real DNS RRs:
example.com. 18000 IN A 127.0.0.1 www.example.com. 60 IN A 6.6.6.6 zone example.com/IN: loaded serial 2026060501 OK
Affected code in 2.3.7:
- lib/Froxlor/Api/Commands/DomainZones.php:92-93 reads record/type from API params.
- lib/Froxlor/Api/Commands/DomainZones.php:122-136 trims/lower-cases/IDNA-encodes record without control-character rejection.
- lib/Froxlor/Api/Commands/DomainZones.php:157-160 hardens content only.
- lib/Froxlor/Api/Commands/DomainZones.php:314-321 and 347-357 store record/type/content into domain_dns_entries.
- lib/Froxlor/Dns/Dns.php:297 passes stored values to DnsEntry.
- lib/Froxlor/Dns/DnsEntry.php:83 concatenates record/type/content into a zone-file line.
There is also a related type-field variant because type is not allowlisted and domain_dns_entries.type is varchar(10). The value NS\tns.\n@\tA renders one submitted entry as multiple zone-file records.
Impact: authenticated customer with DNS-zone permissions can inject additional BIND resource-record lines into the generated zone file for a domain they can manage in Froxlor, bypassing Froxlor's DNS field-level validation. This is DNS zone integrity loss and possible DNS availability impact inside the caller's manageable zone.
Suggested remediation: allowlist DNS RR types, reject CR/LF/HTAB/control chars/spaces/semicolon in record and type, validate record as a DNS owner name while allowing intended cases such as @, *, *.label, _service._proto, _dmarc, and DKIM selectors. Add defense-in-depth in DnsEntry or the DNS serializer so CR/LF cannot reach generated zone lines.
Attribution: Yaohui Wang.
The vulnerability can be exploited over the network without needing physical access. It is easy for an attacker to exploit this vulnerability. An attacker needs basic access or low-level privileges. No user interaction is needed for the attacker to exploit this vulnerability. The impact is confined to the system where the vulnerability exists. There is a low impact on the integrity of the data. There is a low impact on the availability of the system.
Exploitation attempts have been detected. Elevated vigilance and prompt remediation are advised.
The exploit probability is very low. The vulnerability is unlikely to be exploited in the next 30 days.
We did not find any exploit available. Neither in GitHub repositories nor in the Exploit-Database.
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