/ 
Net-DNS-1.34_02
/ axfr
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

axfr - Perform a DNS zone transfer

SYNOPSIS

axfr [ -fqs ] [ -D directory ] [ @nameserver ] zone

DESCRIPTION

axfr performs a DNS zone transfer, prints each record to the standard output, and stores the zone to a file. If the zone has already been stored in a file, axfr will read the file instead of performing a zone transfer.

Zones will be stored in a directory hierarchy. For example, the zone transfer for foo.bar.com will be stored in the file $HOME/.dns-zones/com/bar/foo/axfr. The directory can be changed with the -D option.

This programs requires that the Storable module be installed.

OPTIONS

-f

Force a zone transfer, even if the zone has already been stored in a file.

-q

Be quiet -- don't print the records from the zone.

-s

Perform a zone transfer if the SOA serial number on the nameserver is different than the serial number in the zone file.

-D directory

Store zone files under directory instead of the default directory (see "FILES").

@nameserver

Query nameserver instead of the default nameserver.

FILES

$HOME/.dns-zones

Default directory for storing zone files.

AUTHOR

Michael Fuhr <mike@fuhr.org>

SEE ALSO

perl(1), check_soa, check_zone, mresolv, mx, perldig, Net::DNS, Storable