CVE-2021-4456

Exploitation

Public exploit code exists. CISA's assessment records a public proof of concept. That is not a report of exploitation in the wild.

SSVC decision

• ExploitationpocPublic proof-of-concept exploit code exists. Not a report of exploitation in the wild.
• AutomatableyesAn attacker can reliably automate reconnaissance through exploitation, so this scales.
• Technical ImpactpartialSuccessful exploitation gives limited control of the vulnerable component.

CISA publishes the decision points, not a final SSVC decision. The decision also depends on mission and well-being impact, which is a property of your deployment rather than of the vulnerability.

EPSS probability

0.37% probability of exploitation activity in the next 30 days.

EPSS percentile

Equal to or higher than the score of 31.1% of scored records. A rank, not a probability.

NVD base score

6.5 (CVSS v3.x), scored by the NVD independently of the CNA.

NVD CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N

NVD analysis status

Analyzed. NVD last modified this record on 2026-06-17.

Red Hat severity

No Red Hat rating. Red Hat rates the CVEs that affect its products.

Exploit-prediction scores from FIRST. Independent scoring and analysis status from the NVD. Vendor severity from Red Hat. Exploitation assessment and catalog membership from CISA.

Published

2026-02-27 00:16Z8 MO AGO

Last updated

2026-02-27 16:53Z8 MO AGO

Reserved

2025-05-18

Assigning CNA

CPANSec

Record state

PUBLISHED

Severity

Medium (CVSS 6.5)

CNA CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N

Weaknesses

• CWE-704Incorrect Type Conversion or CastClass

Data version

5.2

Document digest

4a433236dd22acc302d166440d5e724b49e28387fd6d44e737f232684f774d33

• blog.urth.orghttps://blog.urth.org/2021/03/29/security-issues-in-perl-ip-address-distros/related
• github.comhttps://github.com/svarshavchik/Net-CIDR/commit/e3648c6bc6bdd018f90cca4149c467017d42bd10patch
• metacpan.orghttps://metacpan.org/dist/Net-CIDR/changesrelease-notes