/ 
Net-DNS-1.49
/ Net::DNS::RR::SVCB
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::SVCB - DNS SVCB resource record

SYNOPSIS

use Net::DNS;
$rr = Net::DNS::RR->new('name HTTPS SvcPriority TargetName SvcParams');

DESCRIPTION

DNS Service Binding (SVCB) resource record

Service binding and parameter specification via the DNS (SVCB and HTTPS RRs)

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.

SvcPriority

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

The priority of this record (relative to others, with lower values preferred). A value of 0 indicates AliasMode.

TargetName

$rr->targetname( $targetname );
$effecivetarget = $rr->targetname;

The domain name of either the alias target (for AliasMode) or the alternative endpoint (for ServiceMode).

For AliasMode SVCB RRs, a TargetName of "." indicates that the service is not available or does not exist.

For ServiceMode SVCB RRs, a TargetName of "." indicates that the owner name of this record must be used as the effective TargetName.

mandatory, alpn, no-default-alpn, port, ipv4hint, ech, ipv6hint

$rr = Net::DNS::RR->new( 'svcb.example. SVCB 1 svcb.example. port=1234' );

$rr->port(1234);
$octets = $rr->port();	# 0x04 0xD2
$octets = $rr->key3();

Constructor methods for mnemonic SvcParams prescribed by RFC9460. When invoked without arguments, the methods return the value of the underlying key as an uninterpreted octet string. The behaviour with undefined arguments is not specified.

keyNN

$keynn = $rr->keyNN;
$rr->keyNN( $keynn );
$rr->keyNN( undef );

Generic constructor and accessor methods for SvcParams. The key index NN is a decimal integer in the range 0 .. 65535. The method argument is a presentation format character string. The returned value is an uninterpreted octet string. The method returns the undefined value if the key is not present. The specified key will be deleted if the argument is undefined.

COPYRIGHT

Copyright (c)2020-2024 Dick Franks.

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 RFC9460(2)

Service Parameter Keys