CVE-2021-39242: High severity HAProxy HAProxy vulnerability

Published Aug 17, 2021
·
Updated

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 can lead to a situation with an attacker-controlled HTTP Host header, because a mismatch between Host and authority is mishandled.

Affected Software

7 affected componentsFixes available
debian/haproxy
1.8.19-1+deb10u31.8.19-1+deb10u42.2.9-2+deb11u52.6.12-12.6.15-1
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

Remediation

Recommended actions to resolve this vulnerability, in priority order.

  1. Upgrade

    Upgrade debian/haproxy to a version that resolves this vulnerability.

    Fixed in 1.8.19-1+deb10u3Fixed in 1.8.19-1+deb10u4Fixed in 2.2.9-2+deb11u5Fixed in 2.6.12-1Fixed in 2.6.15-1

Event History

Aug 17, 2021
CVE Published
via MITRE·06:33 PM
Data Sourced
via MITRE·06:33 PM
Description
Data Sourced
via NVD·07:15 PM
DescriptionSeverityWeaknessAffected Software

Frequently Asked Questions

1

What is the vulnerability ID of this issue in HAProxy?

The vulnerability ID of this issue in HAProxy is CVE-2021-39242.

2

What is the severity of CVE-2021-39242?

The severity of CVE-2021-39242 is high with a CVSS score of 7.5.

3

How does the vulnerability in HAProxy occur?

The vulnerability in HAProxy occurs due to mishandling of a mismatch between Host and authority when an attacker-controlled HTTP Host header is present.

4

Which versions of HAProxy are affected by CVE-2021-39242?

HAProxy versions before 2.2.16, 2.3.13, and 2.4.3 are affected by CVE-2021-39242.

5

Where can I find more information about CVE-2021-39242?

More information about CVE-2021-39242 can be found at the following references: [link1](https://git.haproxy.org/?p=haproxy.git;a=commit;h=b5d2b9e154d78e4075db163826c5e0f6d31b2ab1), [link2](https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/4ALECUZDIMT5FYGP6V6PVSI4BKVZTZWN/), [link3](https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/RPNY4WZIQUAUOCLIMUPC37AQWNXTWIQM/)

Contact

SecAlerts Pty Ltd.
132 Wickham Terrace
Fortitude Valley,
QLD 4006, Australia
info@secalerts.co
By using SecAlerts services, you agree to our services end-user license agreement. This website is safeguarded by reCAPTCHA and governed by the Google Privacy Policy and Terms of Service. All names, logos, and brands of products are owned by their respective owners, and any usage of these names, logos, and brands for identification purposes only does not imply endorsement. If you possess any content that requires removal, please get in touch with us.
© 2026 SecAlerts Pty Ltd.
ABN: 70 645 966 203, ACN: 645 966 203