/ 
perl-5.45.1
⭐ Starred 2013 / libnetcfg
Security Advisories (1)
CVE-2026-15534 (2026-08-09)

Perl versions through 5.45.1 have out-of-bounds heap reads and writes during regular expression matching via an undersized superlinear cache in S_regmatch. The regex engine's superlinear cache holds one bit per subject position for each participating WHILEM node, so the bit count is the subject length plus one times the number of nodes. Nothing checks that product for positive overflow of the signed 32-bit count: a 286331153 byte subject matched against a pattern with 15 participating nodes stores the count as 14, leaving a two byte cache. The cache is then indexed from the real match position and node number, so reads go past the end of the allocation, and on failure CACHEsayNO sets a bit past it. A caller that matches an attacker controlled subject of this size against a pattern of this shape can crash the process or corrupt heap memory.

NAME

libnetcfg - configure libnet

DESCRIPTION

The libnetcfg utility can be used to configure the libnet. Starting from perl 5.8 libnet is part of the standard Perl distribution, but the libnetcfg can be used for any libnet installation.

USAGE

Without arguments libnetcfg displays the current configuration.

$ libnetcfg
# old config ./libnet.cfg
daytime_hosts        ntp1.none.such
ftp_int_passive      0
ftp_testhost         ftp.funet.fi
inet_domain          none.such
nntp_hosts           nntp.none.such
ph_hosts             
pop3_hosts           pop.none.such
smtp_hosts           smtp.none.such
snpp_hosts           
test_exist           1
test_hosts           1
time_hosts           ntp.none.such
# libnetcfg -h for help
$

It tells where the old configuration file was found (if found).

The -h option will show a usage message.

To change the configuration you will need to use either the -c or the -d options.

The default name of the old configuration file is by default "libnet.cfg", unless otherwise specified using the -i option, -i oldfile, and it is searched first from the current directory, and then from your module path.

The default name of the new configuration file is "libnet.cfg", and by default it is written to the current directory, unless otherwise specified using the -o option, -o newfile.

SEE ALSO

Net::Config, libnetFAQ

AUTHORS

Graham Barr, the original Configure script of libnet.

Jarkko Hietaniemi, conversion into libnetcfg for inclusion into Perl 5.8.