Vulnerability in Mrsam Net\

CVE-2021-4456

Net::CIDR versions before 0.24 for Perl mishandle leading zeros in IP CIDR addresses, which may have unspecified impact. The functions `addr2cidr` and `cidrlookup` may return leading zeros in a CIDR string, which may in turn be parsed as octal numbers by subsequent users. In some cases an attacker may be able to leverage this to bypass access controls based on IP addresses. The documentation advises validating untrusted CIDR strings with the `cidrvalidate` function. However, this mitigation is optional and not enforced by default. In practice, users may call `addr2cidr` or `cidrlookup` with untrusted input and without validation, incorrectly assuming that this is safe.

EPSS: 0.003 (24.7th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 6.5 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N.

Affected products

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2021-4456?
CVE-2021-4456 is a medium-severity vulnerability in Mrsam Net\, classified under Incorrect Type Conversion or Cast. CVSS score: 6.5/10. Published 2026-02-27.
How severe is CVE-2021-4456?
Medium severity. CVSS v3 base score is 6.5 out of 10.