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.

The Unity Linux 20 host has a package installed that is affected by a vulnerability as referenced in the UTSA-2026-017418 advisory.

    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.

Tenable has extracted the preceding description block directly from the Unity Linux security advisory.

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

The remote Red Hat Enterprise Linux CoreOS  host has packages installed that are affected by multiple vulnerabilities as referenced in the RHSA-2021:5208 advisory.

  - haproxy: does not ensure that the scheme and path portions of a URI have the expected characters     (CVE-2021-39240)

  - haproxy: an HTTP method name may contain a space followed by the name of a protected resource     (CVE-2021-39241)

  - haproxy: it can lead to a situation with an attacker-controlled HTTP Host header because a mismatch     between Host and authority is mishandled (CVE-2021-39242)

  - haproxy: request smuggling attack or response splitting via duplicate content-length header     (CVE-2021-40346)

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The remote Red Hat Enterprise Linux CoreOS  host has packages installed that are affected by multiple vulnerabilities as referenced in the RHSA-2021:4118 advisory.

  - haproxy: does not ensure that the scheme and path portions of a URI have the expected characters     (CVE-2021-39240)

  - haproxy: an HTTP method name may contain a space followed by the name of a protected resource     (CVE-2021-39241)

  - haproxy: it can lead to a situation with an attacker-controlled HTTP Host header because a mismatch     between Host and authority is mishandled (CVE-2021-39242)

  - haproxy: request smuggling attack or response splitting via duplicate content-length header     (CVE-2021-40346)

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The remote CentOS Linux 9 host has a package installed that is affected by multiple vulnerabilities as referenced in the haproxy-2.4.7-1.el9 build changelog.

  - 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. (CVE-2021-39240)

  - 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. (CVE-2021-39241)

  - 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. (CVE-2021-39242)

  - An integer overflow exists in HAProxy 2.0 through 2.5 in htx_add_header that can be exploited to perform     an HTTP request smuggling attack, allowing an attacker to bypass all configured http-request HAProxy ACLs     and possibly other ACLs. (CVE-2021-40346)

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The version of haproxy2 installed on the remote host is prior to 2.2.17-1. It is, therefore, affected by multiple vulnerabilities as referenced in the ALAS2HAPROXY2-2023-005 advisory.

    A flaw was found in haproxy. An input validation flaw when processing HTTP/2 requests causes haproxy to     not ensure that the scheme and path portions of a URI have the expected characters.  This may cause     specially crafted input to bypass implemented security restrictions. The highest threat from this     vulnerability is confidentiality. (CVE-2021-39240)

    haproxy has an input validation flaw that could allow a remote attacker to bypass implemented security     restrictions.  An HTTP method name may contain a space followed by the name of a protected resource. Given     this, It is possible that an server would interpret this as a request for that protected resource. The     highest threat from this vulnerability is possible confidentiality concerns. (CVE-2021-39241)

    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. (CVE-2021-39242)

    Proxy server haproxy has a flaw that can could allow an HTTP request smuggling attack with the goal of     bypassing access-control list rules defined by haproxy. The attack was made possible by utilizing an     integer overflow vulnerability that allowed reaching an unexpected state in haproxy while parsing an HTTP     request. The highest threat from this vulnerability is integrity. (CVE-2021-40346)

Tenable has extracted the preceding description block directly from the tested product security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The remote Redhat Enterprise Linux 7 / 8 host has packages installed that are affected by multiple vulnerabilities as referenced in the RHSA-2021:4118 advisory.

  - haproxy: does not ensure that the scheme and path portions of a URI have the expected characters     (CVE-2021-39240)

  - haproxy: an HTTP method name may contain a space followed by the name of a protected resource     (CVE-2021-39241)

  - haproxy: it can lead to a situation with an attacker-controlled HTTP Host header because a mismatch     between Host and authority is mishandled (CVE-2021-39242)

  - haproxy: request smuggling attack or response splitting via duplicate content-length header     (CVE-2021-40346)

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

An update of the haproxy package has been released.

The remote Debian 11 host has packages installed that are affected by multiple vulnerabilities as referenced in the dsa-4960 advisory.

  - 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. (CVE-2021-39240)

  - 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. (CVE-2021-39241)

  - 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. (CVE-2021-39242)

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

ID	Name	Product	Family	Severity
314136	Unity Linux 20.1060e / 20.1070e Security Update: haproxy (UTSA-2026-017418)	Nessus	Unity Linux Local Security Checks	high
312517	RHCOS : OpenShift Container Platform 4.8.25 (RHSA-2021:5208)	Nessus	Red Hat Local Security Checks	high
312459	RHCOS : OpenShift Container Platform 4.9.6 (RHSA-2021:4118)	Nessus	Red Hat Local Security Checks	high
191145	CentOS 9 : haproxy-2.4.7-1.el9	Nessus	CentOS Local Security Checks	high
181935	Amazon Linux 2 : haproxy2 (ALASHAPROXY2-2023-005)	Nessus	Amazon Linux Local Security Checks	high
155292	RHEL 7 / 8 : OpenShift Container Platform 4.9.6 packages and (RHSA-2021:4118)	Nessus	Red Hat Local Security Checks	high
153037	Photon OS 4.0: Haproxy PHSA-2021-4.0-0092	Nessus	PhotonOS Local Security Checks	high
153033	Photon OS 3.0: Haproxy PHSA-2021-3.0-0293	Nessus	PhotonOS Local Security Checks	high
152638	Debian DSA-4960-1 : haproxy - security update	Nessus	Debian Local Security Checks	high

Detections

Analytics

CVE-2021-39240

high

Tenable Plugins

high

high

high

high

high

high

high

high

high