Security Advisories (1)
CVE-2026-81928 (2026-09-01)

Net::DNS versions before 1.57 for Perl allow memory exhaustion via unbounded recursion in sig_data when re-encoding a message with a misplaced TSIG record. sig_data signs a message by re-encoding it, and removes TSIG records only from the additional section. A TSIG decoded into the answer or authority section survives that step and is signed again, so encoding re-enters sig_data with no termination condition. Decoding does not reject such a message: a TSIG that is not the last record on the wire raises "misplaced or corrupt TSIG", but the error is caught, reported as a warning, and the record is left in the packet. RFC 8945 section 5.2 requires the message to be dropped. The recursion is reached only when the decoded TSIG carries an empty MAC, since a MAC recovered from the wire short-circuits the signing step. It is reached only from code that re-encodes a message it decoded, such as a forwarder or a proxy. A decoded message that is never re-encoded is unaffected. Message direction does not matter: a query reaches the same path as a response. Each cycle re-encodes the whole message, so fewer than 100 bytes on the wire exhaust available memory and terminate the process.

NAME

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

SYNOPSIS

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

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

$resolver->hints('198.41.0.4');	# A.ROOT-SERVER.NET.

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

DESCRIPTION

This module resolves queries by following the delegation path from the DNS root.

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 of nameservers to be used to discover the addresses of the root nameservers.

$resolver->hints(@ip);

If no hints are passed, the priming query is directed to nameservers drawn from a built-in list of IP addresses.

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 query packets 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;

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, whose contribution is gratefully acknowledged.

COPYRIGHT

Copyright (c)2014,2019 Dick Franks.

Portions Copyright (c)2002 Rob Brown.

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

Net::DNS::Resolver