CVE-2021-39241: An issue was discovered in HAProxy 2.0 before 2.0.24, 2.2 before 2.2.16, 2.3 before 2.3.13, and 2.4 before 2.4.3. An HTTP method name may contain a sp...

Description

An issue was discovered in HAProxy 2.0 before 2.0.24, 2.2 before 2.2.16, 2.3 before 2.3.13, and 2.4 before 2.4.3. An HTTP method name may contain a space followed by the name of a protected resource. It is possible that a server would interpret this as a request for that protected resource, such as in the "GET /admin? HTTP/1.1 /static/images HTTP/1.1" example.

Metrics

CVSS 3.1

5.3/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

EPSS Probability

1.76%

75.1th percentile

Probability of exploitation in the next 30 days. Learn more

Affected Software

Vendor	Product	Versions
Haproxy	Haproxy	>= 2.0.0, < 2.0.24
Haproxy	Haproxy	>= 2.2.0, < 2.2.16
Haproxy	Haproxy	>= 2.3.0, < 2.3.13
Haproxy	Haproxy	>= 2.4.0, < 2.4.3
Debian	Debian Linux	11.0
Fedoraproject	Fedora	33
Fedoraproject	Fedora	34

References

Timeline

Published: Aug 17, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-39241?

An issue was discovered in HAProxy 2.0 before 2.0.24, 2.2 before 2.2.16, 2.3 before 2.3.13, and 2.4 before 2.4.3. An HTTP method name may contain a space followed by the name of a protected resource. It is possible that a server would interpret this as a request for that protected resource, such as in the "GET /admin? HTTP/1.1 /static/images HTTP/1.1" example.

How severe is CVE-2021-39241?

CVE-2021-39241 has a CVSS score of 5.3/10 (MEDIUM severity). The EPSS model estimates a 1.76% probability of exploitation in the next 30 days.

How do I fix CVE-2021-39241?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.