What is CVE-2021-21956?

CVE-2021-21956 is a high-severity vulnerability in Cloudlinux Imunify360, classified under Deserialization of Untrusted Data. CVSS score: 7.8/10. Published 2022-04-14.

How severe is CVE-2021-21956?

High severity. CVSS v3 base score is 7.8 out of 10.

Deserialization in Cloudlinux Imunify360

CVE-2021-21956

A php unserialize vulnerability exists in the Ai-Bolit functionality of CloudLinux Inc Imunify360 5.10.2. A specially-crafted malformed file can lead to potential arbitrary command execution. An attacker can provide a malicious file to trigger this vulnerability.

Vulnerability class: Insecure Deserialization

Published 2022-04-14 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 7.8 (High). Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.014 (71.5th percentile), scored 2026-10-08.

Low probability of exploitation in the next 30 days, but still tracked. 72nd percentile — 71.5% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.014 · newest: 0.014 · change: 0.000

Affected products

Cloudlinux Imunify360 — versions 5.8, 5.9, 5.10.2
Cloudlinux Inc Imunify360 — versions 5.8, 5.9

Weakness classification (CWE)

CWE-502 — Deserialization of Untrusted Data

References

talosintelligence.com/vulnerability_reports/TALOS-2021-1383 (Exploit, Third Party Advisory)

Frequently asked questions

What is CVE-2021-21956?: CVE-2021-21956 is a high-severity vulnerability in Cloudlinux Imunify360, classified under Deserialization of Untrusted Data. CVSS score: 7.8/10. Published 2022-04-14.
How severe is CVE-2021-21956?: High severity. CVSS v3 base score is 7.8 out of 10.