CVE-2021-39241

Severity: medium (CVSS 5.3 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 1.7% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2021-08-17 · updated 2026-06-17

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.

Affected products

Debian Linux: 11.0
Fedoraproject Fedora: 33, 34
HAProxy: from 2.0.0 before 2.0.24; from 2.2.0 before 2.2.16; from 2.3.0 before 2.3.13; from 2.4.0 before 2.4.3 — fixed in 2.0.24, 2.2.16, 2.3.13, 2.4.3

How to fix

Upgrade to a fixed version: HAProxy 2.0.24, 2.2.16, 2.3.13, 2.4.3. Check the vendor advisory for mitigations.

References

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