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::NSEC3 - DNS NSEC3 resource record

SYNOPSIS

use Net::DNS;
$rr = Net::DNS::RR->new('name NSEC3 algorithm flags iterations salt hnxtname');

DESCRIPTION

Class for DNSSEC NSEC3 resource records.

The NSEC3 Resource Record (RR) provides authenticated denial of existence for DNS Resource Record Sets.

The NSEC3 RR lists RR types present at the original owner name of the NSEC3 RR. It includes the next hashed owner name in the hash order of the zone. The complete set of NSEC3 RRs in a zone indicates which RRSets exist for the original owner name of the RR and form a chain of hashed owner names in the zone.

METHODS

The available methods are those inherited from the base class augmented by the type-specific methods defined in this package.

Use of undocumented package features or direct access to internal data structures is discouraged and could result in program termination or other unpredictable behaviour.

algorithm

$algorithm = $rr->algorithm;
$rr->algorithm( $algorithm );

The Hash Algorithm field is represented as an unsigned decimal integer. The value has a maximum of 255.

algorithm() may also be invoked as a class method or simple function to perform mnemonic and numeric code translation.

flags

$flags = $rr->flags;
$rr->flags( $flags );

The Flags field is an unsigned decimal integer interpreted as eight concatenated Boolean values.

optout
 $rr->optout(1);

 if ( $rr->optout ) {
	...
 }

Boolean Opt Out flag.

iterations

$iterations = $rr->iterations;
$rr->iterations( $iterations );

The Iterations field is represented as an unsigned decimal integer. The value is between 0 and 65535, inclusive.

salt

$salt = $rr->salt;
$rr->salt( $salt );

The Salt field is represented as a contiguous sequence of hexadecimal digits. A "-" (unquoted) is used in string format to indicate that the salt field is absent.

saltbin

$saltbin = $rr->saltbin;
$rr->saltbin( $saltbin );

The Salt field as a sequence of octets.

hnxtname

$hnxtname = $rr->hnxtname;
$rr->hnxtname( $hnxtname );

The Next Hashed Owner Name field points to the next node that has authoritative data or contains a delegation point NS RRset.

typelist

@typelist = $rr->typelist;
$typelist = $rr->typelist;
$rr->typelist( @typelist );

typelist() identifies the RRset types that exist at the domain name matched by the NSEC3 RR. When called in scalar context, the list is interpolated into a string.

typemap

$exists = $rr->typemap($rrtype);

typemap() returns a Boolean true value if the specified RRtype occurs in the type bitmap of the NSEC3 record.

match

$matched = $rr->match( 'example.foo' );

match() returns a Boolean true value if the hash of the domain name argument matches the hashed owner name of the NSEC3 RR.

covers

$covered = $rr->covers( 'example.foo' );

covers() returns a Boolean true value if the hash of the domain name argument, or ancestor of that name, falls between the owner name and the next hashed owner name of the NSEC3 RR.

encloser, nextcloser, wildcard

$encloser = $rr->encloser( 'example.foo' );
print "encloser: $encloser\n" if $encloser;

encloser() returns the name of a provable encloser of the query name argument obtained from the NSEC3 RR.

nextcloser() returns the next closer name, which is one label longer than the closest encloser. This is only valid after encloser() has returned a valid domain name.

wildcard() returns the unexpanded wildcard name from which the next closer name was possibly synthesised. This is only valid after encloser() has returned a valid domain name.

COPYRIGHT

Copyright (c)2017,2018 Dick Franks

Portions Copyright (c)2007,2008 NLnet Labs. Author Olaf M. Kolkman

All rights reserved.

Package template (c)2009,2012 O.M.Kolkman and R.W.Franks.

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::DNS::RR RFC5155 RFC9077

Hash Algorithms