modcluster mod_proxy_cluster Response Body crlf injection

Summaryinfo

A vulnerability was found in modcluster mod_proxy_cluster. It has been rated as problematic. Affected by this vulnerability is an unknown functionality of the component Response Body Handler. The manipulation leads to crlf injection. This vulnerability is listed as CVE-2026-3234. The attack may be initiated remotely. There is no available exploit.

Detailsinfo

A vulnerability was found in modcluster mod_proxy_cluster (version unknown) and classified as problematic. This issue affects an unknown function of the component Response Body Handler. The manipulation with an unknown input leads to a crlf injection vulnerability. Using CWE to declare the problem leads to CWE-93. The product uses CRLF (carriage return line feeds) as a special element, e.g. to separate lines or records, but it does not neutralize or incorrectly neutralizes CRLF sequences from inputs. Impacted is integrity. The summary by CVE is:

A flaw was found in mod_proxy_cluster. This vulnerability, a Carriage Return Line Feed (CRLF) injection in the decodeenc() function, allows a remote attacker to bypass input validation. By injecting CRLF sequences into the cluster configuration, an attacker can corrupt the response body of INFO endpoint responses. Exploitation requires network access to the MCMP protocol port, but no authentication is needed.

It is possible to read the advisory at bugzilla.redhat.com. The identification of this vulnerability is CVE-2026-3234. The exploitation is known to be difficult. The attack may be initiated remotely. No form of authentication is needed for a successful exploitation. The technical details are unknown and an exploit is not publicly available. The pricing for an exploit might be around USD $0-$5k at the moment (estimation calculated on 03/17/2026).

The vulnerability scanner Nessus provides a plugin with the ID 301042 (Linux Distros Unpatched Vulnerability : CVE-2026-3234), which helps to determine the existence of the flaw in a target environment.

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

The vulnerability is also documented in the vulnerability database at Tenable (301042). Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

Productinfo

Type

• Firewall Software

Vendor

• modcluster

Name

• mod_proxy_cluster

CPE 2.3info

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CPE 2.2info

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Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

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