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CVE-2021-39240

7.5 · HIGH

An issue was discovered in HAProxy 2.2 before 2.2.16, 2.3 before 2.3.13, and 2.4 before 2.4.3.

Published Aug 17, 2021EPSS 2.21%

Overview

CVE-2021-39240 is a high-severity vulnerability. It was published on August 17, 2021 and has a CVSS 3.1 base score of 7.5 (HIGH).

This vulnerability has a CVSS 3.1 base score of 7.5, rated HIGH. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

Technical description

An issue was discovered in HAProxy 2.2 before 2.2.16, 2.3 before 2.3.13, and 2.4 before 2.4.3. It does not ensure that the scheme and path portions of a URI have the expected characters. For example, the authority field (as observed on a target HTTP/2 server) might differ from what the routing rules were intended to achieve.

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References

Refgit.haproxy.org/?p=haproxy.git%3Ba=commit%3Bh=4b8852c70d8c4b7e225e24eb58258a15eb54c26eRefgit.haproxy.org/?p=haproxy.git%3Ba=commit%3Bh=a495e0d94876c9d39763db319f609351907a31e8Reflists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/4ALECUZDIMT5FYGP6V6PVSI4BKVZTZWN/Reflists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/RPNY4WZIQUAUOCLIMUPC37AQWNXTWIQM/Refwww.debian.org/security/2021/dsa-4960Refwww.mail-archive.com/haproxy%40formilux.org/msg41041.htmlRefgit.haproxy.org/?p=haproxy.git%3Ba=commit%3Bh=4b8852c70d8c4b7e225e24eb58258a15eb54c26eRefgit.haproxy.org/?p=haproxy.git%3Ba=commit%3Bh=a495e0d94876c9d39763db319f609351907a31e8Reflists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/4ALECUZDIMT5FYGP6V6PVSI4BKVZTZWN/Reflists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/RPNY4WZIQUAUOCLIMUPC37AQWNXTWIQM/

How CyberStrike helps

Frequently asked questions

What is CVE-2021-39240?

CVE-2021-39240 is a high-severity vulnerability. It was published on August 17, 2021 and has a CVSS 3.1 base score of 7.5 (HIGH).

How severe is CVE-2021-39240?

This vulnerability has a CVSS 3.1 base score of 7.5, rated HIGH. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

How do I fix or remediate CVE-2021-39240?

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

How can CyberStrike help with CVE-2021-39240?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2021-39240 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.

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