/ 
Net-DNS-0.67_03
/ Net::DNS::RR::TXT
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::RR::TXT - DNS TXT resource record

SYNOPSIS

use Net::DNS::RR;

DESCRIPTION

Class for DNS Text (TXT) resource records.

METHODS

txtdata

print "txtdata = ", $rr->txtdata, "\n";

Returns the descriptive text as a single string, regardless of actual number of <character-string> elements. Of questionable value. Should be deprecated.

Use $txt->rdatastr() or $txt->char_str_list() instead.

char_str_list

print "Individual <character-string> list: \n\t",
      join("\n\t", $rr->char_str_list());

Returns a list of the individual <character-string> elements, as unquoted strings. Used by TXT->rdatastr and TXT->rr_rdata.

NB: rdatastr will return quoted strings.

FEATURES

The RR.pm module accepts semi-colons as a start of a comment. This is to allow the RR.pm to deal with RFC1035 specified zonefile format.

For some applications of the TXT RR the semicolon is relevant, you will need to escape it on input.

Also note that you should specify the several character strings separately. The easiest way to do so is to include the whole argument in single quotes and the several character strings in double quotes. Double quotes inside the character strings will need to be escaped.

my $TXTrr=Net::DNS::RR->new('txt2.t.net-dns.org. 60 IN TXT "Test1 \" \; more stuff" "Test2"');

would result in $TXTrr->char_str_list())[0] containing 'Test1 " ; more stuff' and $TXTrr->char_str_list())[1] containing 'Test2'

Note that the rdatastr method (and therefore the print, and string method) returns the escaped format.

COPYRIGHT

Copyright (c) 1997-2002 Michael Fuhr.

Portions Copyright (c) 2002-2004 Chris Reinhardt. Portions Copyright (c) 2005 Olaf Kolkman (NLnet Labs)

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

perl(1), Net::DNS, Net::DNS::Resolver, Net::DNS::Packet, Net::DNS::Header, Net::DNS::Question, Net::DNS::RR, RFC 1035 Section 3.3.14