/ 
Net-DNS-1.55_01
/ axfr
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

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