Skip to content
Fencer Vulns
high 7.5

CVE-2021-29424 json

The Net::Netmask module before 2.0000 for Perl does not properly consider extraneous zero characters at the beginning of an IP address stri…

published 2021-03-29 5 y ago modified 2026-06-17 4 mo ago also EUVD-2021-16056

cvss
7.5
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
1.8%
EPSS 1.8% chance of exploitation in 30 days, percentile 78%
public exploits
0
none known

Summary

The Net::Netmask module before 2.0000 for Perl does not properly consider extraneous zero characters at the beginning of an IP address string, which (in some situations) allows attackers to bypass access control that is based on IP addresses.

Patch / fix

  • net::netmask_project net::netmask 2.0000
  • libnet-netmask-perl Debian 14, Debian 13, Debian 12 1.9104-2

debian advisories DEBIAN-CVE-2021-29424

  • perl-Net-Netmask Package Hub 15 SP5, openSUSE Leap 15.5 1.9022-bp155.3.3.1
  • perl-Net-Netmask Package Hub 15 SP4, openSUSE Leap 15.4 1.9022-bp154.2.3.1

opensuse advisories openSUSE-SU-2023:0217-1openSUSE-SU-2023:0215-1

  • perl-net-netmask Alpine 3.24 2.0000-r0

alpine advisories ALPINE-CVE-2021-29424

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2021-29424 updated cvss 7.5

perl-Net-Netmask: incorrectly parses an IP address with leading zeros in IP octets

  • Red Hat All currently supported Red Hat products
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

1.80% chance of exploitation in the next 30 days, higher than 78% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • blog.urth.org https://blog.urth.org/2021/03/29/security-issues-in-perl-ip-address-distros/ referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
NVD 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
NVD 2.0 5.0 AV:N/AC:L/Au:N/C:N/I:P/A:N

Classification

Weakness
  • CWE-704 Incorrect Type Conversion or Cast

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.