/ 
Net-DNS-0.81_01
/ Net::DNS::Resolver::Recurse
Security Advisories (2)
CVE-2026-64193 (2026-07-20)

Net::DNS versions through 1.55 for Perl allow remote execution injection via EDNS EXTENDED ERROR. Net::DNS::RR::OPT::EXTENDED_ERROR::_decompose parses the EXTRA-TEXT field of an EDNS EXTENDED-ERROR option (RFC 8914) by tokenising the raw bytes and passing the result to Perl's eval. There is some escaping done for $ and @, but not for backticks. This can be exploited for command execution if $pkt->edns->option('EXTENDED-ERROR') is called in array context, for example with a payload of {0:`"<command>"`} in EXTRA-TEXT.

CVE-2026-64194 (2026-07-20)

Net::DNS versions through 1.55 for Perl allow Denial of Service via deep DNS compression pointer chains. Net::DNS::DomainName::decode follows RFC 1035 compression pointers by recursing into itself with no depth limit. It is possible to construct a name which saturates the call stack (at least with larger TCP responses), leading to a potential Denial of Service. The guard `$link < $offset` prevents forward and circular chains, but still allows arbitrarily long backward chains. The per-offset cache (`$cache`) is populated at the start of each call and short-circuits only re-traverses of the same offset - the initial descent through a fresh chain still recurses at full depth. A crafted packet can chain two-byte compression pointers so that each one points two bytes earlier than the previous, producing a chain length of `offset / 2`. For the 14-bit pointer field (max offset 16383) this gives up to ~8191 recursive frames. For a TCP DNS message the limit is the 16-bit length field (~32767 frames). Perl's default C stack handles only a few thousand frames; beyond that the process receives SIGSEGV or similar, which is a denial-of-service for any application parsing untrusted DNS data. The vulnerability is triggered by `Net::DNS::Packet->new(\$wire)` i.e. any point where the library decodes a DNS message from the network.

NAME

Net::DNS::Resolver::Recurse - DNS recursive resolver

SYNOPSIS

use Net::DNS::Resolver::Recurse;

$resolver = new Net::DNS::Resolver::Recurse();

$packet = $resolver->query ( 'www.example.com', 'A' );
$packet = $resolver->search( 'www.example.com', 'A' );
$packet = $resolver->send  ( 'www.example.com', 'A' );

DESCRIPTION

This module is a subclass of Net::DNS::Resolver.

METHODS

This module inherits almost all the methods from Net::DNS::Resolver. Additional module-specific methods are described below.

hints

This method specifies a list of the IP addresses used to locate the authoritative name servers for the root (.) zone.

$resolver->hints(@ip);

If no hints are passed, the default nameserver is used to discover the addresses of the root nameservers.

If the default nameserver not been configured correctly, or at all, a built-in list of IP addresses is used.

query, search, send

The query(), search() and send() methods produce the same result as their counterparts in Net::DNS::Resolver.

$packet = $resolver->send( 'www.example.com.', 'A' );

Server-side recursion is suppressed by clearing the recurse flag in the packet and recursive name resolution is performed explicitly.

The query() and search() methods are inherited from Net::DNS::Resolver and invoke send() indirectly.

callback

This method specifies a code reference to a subroutine, which is then invoked at each stage of the recursive lookup.

For example to emulate dig's +trace function:

    my $coderef = sub {
	my $packet = shift;

	$_->print for $packet->additional;

	printf ";; Received %d bytes from %s\n\n",
		$packet->answersize, $packet->answerfrom;
    };

    $resolver->callback($coderef);

The callback subroutine is not called for queries for missing glue records.

ACKNOWLEDGEMENT

This package is an improved and compatible reimplementation of the Net::DNS::Resolver::Recurse.pm created by Rob Brown in 2002.

The contribution of Rob Brown is gratefully acknowledged.

COPYRIGHT

Copyright (c)2014 Dick Franks

Portions Copyright (c)2002 Rob Brown

All rights reserved.

This program is free software; you may redistribute it and/or modify it under the same terms as Perl itself.

SEE ALSO

Net::DNS::Resolver