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Findings

CVE-2021-4456

Net::CIDR versions before 0.24 for Perl mishandle leading zeros in IP CIDR addresses, which may have unspecified impact.

Published Feb 27, 2026 · updated Jun 17, 2026 · mrsam net

Net::CIDR versions before 0.24 for Perl mishandle leading zeros in IP CIDR addresses, which may have unspecified impact. The functions and 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 function. However, this mitigation is optional and not enforced by default. In practice, users may call or with untrusted input and without validation, incorrectly assuming that this is safe.

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. Feb 27, 2026 · NIST NVD

    Detected

    Net::CIDR versions before 0.24 for Perl mishandle leading zeros in IP CIDR addresses, which may have unspecified impact. The functions and 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 C

  2. Jun 17, 2026 · NIST NVD

    Updated

    Net::CIDR versions before 0.24 for Perl mishandle leading zeros in IP CIDR addresses, which may have unspecified impact. The functions and 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 C

Affected

  • cpe mrsam/net\

Sources

  • CVE.orgVulnerability recordCVE-2021-4456

    Official CVE identifier

    cve.org
  • NIST NVDVulnerability recordCVE-2021-4456

    Net::CIDR versions before 0.24 for Perl mishandle leading zeros in IP CIDR addresses, which may have unspecified impact. The functions and may return leading zeros in a CIDR string, which may in turn be parsed as octal numbers by subsequent users. In som

    nvd.nist.gov

References