What is CVE-2020-18440?

CVE-2020-18440 is a critical-severity vulnerability in Phpok, classified under Buffer Copy without Checking Size of Input (Classic Buffer Overflow). CVSS score: 9.8/10. Published 2021-11-02.

How severe is CVE-2020-18440?

Critical severity. CVSS v3 base score is 9.8 out of 10.

Buffer overflow in Phpok

CVE-2020-18440

Buffer overflow vulnerability in framework/init.php in qinggan phpok 5.1, allows attackers to execute arbitrary code.

Vulnerability class: Buffer Overflow

Published 2021-11-02 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.017 (75.7th percentile), scored 2026-09-30.

Low probability of exploitation in the next 30 days, but still tracked. 76th percentile — 75.7% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.017 · newest: 0.017 · change: 0.000

Affected products

Phpok — versions 5.1

Weakness classification (CWE)

CWE-120 — Buffer Copy without Checking Size of Input (Classic Buffer Overflow)

References

github.com/qinggan/phpok/issues/4 (Exploit, Third Party Advisory, Issue Tracking)

Frequently asked questions

What is CVE-2020-18440?: CVE-2020-18440 is a critical-severity vulnerability in Phpok, classified under Buffer Copy without Checking Size of Input (Classic Buffer Overflow). CVSS score: 9.8/10. Published 2021-11-02.
How severe is CVE-2020-18440?: Critical severity. CVSS v3 base score is 9.8 out of 10.