/ 
Net-DNS-1.33
/ Net::DNS::Domain
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::Domain - DNS domains

SYNOPSIS

use Net::DNS::Domain;

$domain = Net::DNS::Domain->new('example.com');
$name   = $domain->name;

DESCRIPTION

The Net::DNS::Domain module implements a class of abstract DNS domain objects with associated class and instance methods.

Each domain object instance represents a single DNS domain which has a fixed identity throughout its lifetime.

Internally, the primary representation is a (possibly empty) list of ASCII domain name labels, and optional link to an origin domain object topologically closer to the DNS root.

The computational expense of Unicode character-set conversion is partially mitigated by use of caches.

METHODS

new

$object = Net::DNS::Domain->new('example.com');

Creates a domain object which represents the DNS domain specified by the character string argument. The argument consists of a sequence of labels delimited by dots.

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

Arbitrary 8-bit codes can be represented by \ followed by exactly three decimal digits. Character code points are ASCII, irrespective of the character coding scheme employed by the underlying platform.

Argument string literals should be delimited by single quotes to avoid escape sequences being interpreted as octal character codes by the Perl compiler.

The character string presentation format follows the conventions for zone files described in RFC1035.

Users should be aware that non-ASCII domain names will be transcoded to NFC before encoding, which is an irreversible process.

name

$name = $domain->name;

Returns the domain name as a character string corresponding to the "common interpretation" to which RFC1034, 3.1, paragraph 9 alludes.

Character escape sequences are used to represent a dot inside a domain name label and the escape character itself.

Any non-printable code point is represented using the appropriate numerical escape sequence.

fqdn

@fqdn = $domain->fqdn;

Returns a character string containing the fully qualified domain name, including the trailing dot.

xname

$xname = $domain->xname;

Interprets an extended name containing Unicode domain name labels encoded as Punycode A-labels.

If decoding is not possible, the ACE encoded name is returned.

label

@label = $domain->label;

Identifies the domain by means of a list of domain labels.

string

$string = $object->string;

Returns a character string containing the fully qualified domain name as it appears in a zone file.

Characters which are recognised by RFC1035 zone file syntax are represented by the appropriate escape sequence.

origin

$create = Net::DNS::Domain->origin( $ORIGIN );
$result = &$create( sub{ Net::DNS::RR->new( 'mx MX 10 a' ); } );
$expect = Net::DNS::RR->new( "mx.$ORIGIN. MX 10 a.$ORIGIN." );

Class method which returns a reference to a subroutine wrapper which executes a given constructor in a dynamically scoped context where relative names become descendents of the specified $ORIGIN.

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)2009-2011,2017 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 original copyright notices appear in all copies and that both 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, Net::LibIDN2, RFC1034, RFC1035, RFC5891, Unicode TR#16