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.
Published · last modified .
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.
EPSS exploit prediction
EPSS: 0.003 (24.3th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 24th percentile — 24.3% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.003 · newest: 0.003 · change: +0.000
Affected products
- Mrsam Net\ — versions \
- Mrsam Net::cidr — versions 0
- Mrsam Net\:\:cidr
Weakness classification (CWE)
References
- 9b29abf9-4ab0-4765-b253-1875cd9b441e (related, Third Party Advisory)
- 9b29abf9-4ab0-4765-b253-1875cd9b441e (Patch, patch)
- 9b29abf9-4ab0-4765-b253-1875cd9b441e (release-notes, Release Notes)
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.