What is CVE-2021-33563?

CVE-2021-33563 is a high-severity vulnerability in Koel, classified under Use of Password Hash With Insufficient Computational Effort. CVSS score: 7.5/10. Published 2021-05-24.

How severe is CVE-2021-33563?

High severity. CVSS v3 base score is 7.5 out of 10.

Vulnerability in Koel

CVE-2021-33563

Koel before 5.1.4 lacks login throttling, lacks a password strength policy, and shows whether a failed login attempt had a valid username. This might make brute-force attacks easier.

Published 2021-05-24 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N.

EPSS exploit prediction

EPSS: 0.008 (56.1th percentile), scored 2026-10-18.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 56th percentile — 56.1% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.008 · newest: 0.008 · change: 0.000

Affected products

Koel

Weakness classification (CWE)

CWE-916 — Use of Password Hash With Insufficient Computational Effort

References

huntr.dev/bounties/1-other-koel/koel/ (Exploit, Third Party Advisory, Issue Tracking)
github.com/koel/koel/releases/tag/v5.1.4 (Third Party Advisory)

Frequently asked questions

What is CVE-2021-33563?: CVE-2021-33563 is a high-severity vulnerability in Koel, classified under Use of Password Hash With Insufficient Computational Effort. CVSS score: 7.5/10. Published 2021-05-24.
How severe is CVE-2021-33563?: High severity. CVSS v3 base score is 7.5 out of 10.