CVE-2021-33563
Improper rate limiting in Koel
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.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- None
- User interaction
- None
What an attacker can affect
- Confidentiality
- High
- Integrity
- None
- Availability
- None
Exploit likelihood
What each source reports
NVD Score used
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.
- Record
CVE-2021-33563- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N - CVSS 2.0
- 5.0 Medium
AV:N/AC:L/Au:N/C:P/I:N/A:N - Weakness
- CWE-916
- Updated
- 2026-11-02
CVE List No score
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.
- Record
CVE-2021-33563- Updated
- 2026-11-02
EUVDEUVD-2021-1390 No score
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.
- Record
EUVD-2021-1390- Updated
- 2026-11-03
GitHub AdvisoriesGHSA-r37h-j483-cjjm No score
Improper rate limiting in Koel
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.
- Record
GHSA-r37h-j483-cjjm- Weakness
- CWE-799, CWE-916
- Updated
- 2026-11-02
OSV
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.
- Record
CVE-2021-33563- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N - Updated
- 2026-11-02
OSVGHSA-r37h-j483-cjjm No score
Improper rate limiting in Koel
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.
- Record
GHSA-r37h-j483-cjjm- Weakness
- CWE-799, CWE-916
- Updated
- 2026-11-02
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
phanan/koelPackagist |
before 5.1.4 | 5.1.4 |
phanan/koelPackagist |
before 5.1.4, plus listed versions 1.0.0-betav0.0.0-betav1.1.1v1.1.2v2.0.0 Show 42 moreShow lessv2.0.1v2.0.2v2.1.0v2.2.0v2.2.1v3.0.0v3.0.1v3.1.0v3.1.1v3.2.0v3.3.0v3.3.1v3.4.0v3.4.1v3.5.0v3.5.1v3.5.2v3.5.3v3.5.4v3.5.5v3.6.0v3.6.1v3.6.2v3.7.0v3.7.1v3.7.2v4.0.0v4.1.0v4.1.1v4.2.0v4.2.1v4.2.2v4.3.0v4.3.1v4.4.0v5.0.0v5.0.1v5.0.2v5.1.0v5.1.1v5.1.2v5.1.3 |
5.1.4 |
History
| Recorded | Changed | Sources |
|---|---|---|
| aliases | EUVD | |
| first indexed | CVE List, GitHub Advisories, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2021-33563 is a high vulnerability (CVSS 7.5) in Koel, published May 24, 2021. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.81%, the 57th percentile. Fixed in phanan/koel 5.1.4.