CVE-2021-4456
MEDIUMCVSS Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
Lifecycle Timeline
3Description
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.
Analysis
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. [CVSS 6.5 MEDIUM]
Technical Context
Classified as CWE-704 (Incorrect Type Conversion or Cast). Affects Net\. 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
Affected Products
Vendor: Mrsam. Product: Net\. Versions: up to \.
Remediation
A vendor patch is available — apply it immediately. Restrict network access to the affected service where possible.
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External POC / Exploit Code
Leaving vuln.today