# CVE-2026-3234: Mod_proxy_cluster: mod_proxy_cluster: response body corruption via crlf injection

Status: published. Published: 2026-03-12. Updated: 2026-11-02.

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.

## Remediation

- workaround: Restrict network access to the MCMP protocol port (typically 6666) for systems running Apache mod_proxy_cluster. Configure firewall rules to limit inbound connections to this port only from trusted internal or management networks. This action reduces the attack surface by preventing unauthorized remote access to the vulnerable service. A service reload or restart may be required for firewall changes to take full effect. (source: CNA: redhat)

## Affected products and versions

- Red Hat / Red Hat Enterprise Linux 10 (mod_proxy_cluster): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 9 (mod_proxy_cluster): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat JBoss Core Services (jbcs-httpd24-mod_proxy_cluster): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat JBoss Core Services (mod_proxy_cluster): Version range not reported. Source: CNA: redhat

## Severity and prioritization

- CVSS 3.1: 4.3 (medium); CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N; source: CNA: redhat

- CISA KEV: No listing in collected sources

- EPSS: 0.33% as of 2026-11-01; percentile 26.19%

- SSVC: exploitation none; automatable no; technical impact partial; source ADP: CISA-ADP

- Weaknesses: CWE-93

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://access.redhat.com/security/cve/CVE-2026-3234 (CNA: redhat; vdb-entry, x_refsource_REDHAT)

- https://bugzilla.redhat.com/show_bug.cgi?id=2442889 (CNA: redhat; issue-tracking, x_refsource_REDHAT)

## Provenance

- CNA: redhat: https://www.cve.org/CVERecord?id=CVE-2026-3234; retrieved 2026-11-02; source updated 2026-11-02

- FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2026-3234; retrieved 2026-11-02; source updated Not reported

Revision: 83cf6b35bc41f5aa8970634575118f721566ad7ca4efcb8beaba2a6a85b0bfbd

Canonical: https://y2.dev/cve/CVE-2026-3234