Improper rate limiting in Koel

published 2021-05-24 5 y ago modified 2026-06-17 4 mo ago also GHSA-r37h-j483-cjjm , EUVD-2021-1390

cvss: 7.5; version 3.1, NVD
cisa kev: Not listed; not in CISA's catalog
epss: 0.8%; EPSS 0.8% chance of exploitation in 30 days, percentile 57%
public exploits: 0; none known

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.

Patch / fix

fixed in 2 links 1

packagist phanan/koel 5.1.4
koel koel 5.1.4

github.com/koel/koel/releases/tag/v5.1.4 release

Exploit prediction

0.81% chance of exploitation in the next 30 days, higher than 57% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

huntr.dev https://huntr.dev/bounties/1-other-koel/koel/ referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by	version	score	vector
NVD	3.1	7.5	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
NVD	2.0	5.0	AV:N/AC:L/Au:N/C:P/I:N/A:N

Affected packages

ecosystem	package	affected	fixed in
packagist	phanan/koel	<5.1.4	5.1.4

Classification

Weakness

CWE-916 Use of Password Hash With Insufficient Computational Effort
CWE-799 Improper Control of Interaction Frequency

References

huntr.dev /bounties/1-other-koel/koel/
exploit, issue-tracking, third-party-advisory
github.com /koel/koel/releases/tag/v5.1.4
web, third-party-advisory
nvd.nist.gov /vuln/detail/CVE-2021-33563
advisory
huntr.dev /bounties/1-other-koel/koel
web

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary