/ 
Net-DNS-1.11_04
/ Net::DNS::Text
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::Text - DNS text representation

SYNOPSIS

use Net::DNS::Text;

$object = new Net::DNS::Text('example');
$string = $object->string;

$object = decode Net::DNS::Text( \$data, $offset );
( $object, $next ) = decode Net::DNS::Text( \$data, $offset );

$data = $object->encode;
$text = $object->value;

DESCRIPTION

The Net::DNS::Text module implements a class of text objects with associated class and instance methods.

Each text object instance has a fixed identity throughout its lifetime.

METHODS

new

$object = new Net::DNS::Text('example');

Creates a text object which encapsulates a single character string component of a resource record.

Arbitrary single-byte characters can be represented by \ followed by exactly three decimal digits. Such characters are devoid of any special meaning.

A character preceded by \ represents itself, without any special interpretation.

decode

$object = decode Net::DNS::Text( \$buffer, $offset );

( $object, $next ) = decode Net::DNS::Text( \$buffer, $offset );

Creates a text object which represents the decoded data at the indicated offset within the data buffer.

The argument list consists of a reference to a scalar containing the wire-format data and offset of the text data.

The returned offset value indicates the start of the next item in the data buffer.

encode

$data = $object->encode;

Returns the wire-format encoded representation of the text object suitable for inclusion in a DNS packet buffer.

raw

$data = $object->raw;

Returns the wire-format encoded representation of the text object without the explicit length field.

value

$value = $text->value;

Character string representation of the text object.

string

$string = $text->string;

Conditionally quoted zone file representation of the text object.

BUGS

Coding strategy is intended to avoid creating unnecessary argument lists and stack frames. This improves efficiency at the expense of code readability.

Platform specific character coding features are conditionally compiled into the code.

COPYRIGHT

Copyright (c)2009-2011 Dick Franks.

All rights reserved.

LICENSE

Permission to use, copy, modify, and distribute this software and its documentation for any purpose and without fee is hereby granted, provided that the above copyright notice appear in all copies and that both that copyright notice and this permission notice appear in supporting documentation, and that the name of the author not be used in advertising or publicity pertaining to distribution of the software without specific prior written permission.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

SEE ALSO

perl, Net::DNS, RFC1035, RFC3629, Unicode Technical Report #16