CRLF Injection Affecting modcluster/mod_proxy_cluster package, versions [0,]
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Test your applications- Snyk IDSNYK-UNMANAGED-MODCLUSTERMODPROXYCLUSTER-15440519
- published8 Mar 2026
- disclosed26 Feb 2026
- creditUnknown
Introduced: 26 Feb 2026
CVE-2026-3234 (opens in a new tab)How to fix?
There is no fixed version for modcluster/mod_proxy_cluster.
Overview
Affected versions of this package are vulnerable to CRLF Injection via the MCMP protocol handling process. An attacker can manipulate HTTP response headers by injecting carriage return and line feed (CRLF) sequences into the response body, potentially leading to response splitting or header corruption when sending specially crafted requests to the affected service.
Workaround
This vulnerability can be mitigated by restricting network access to the MCMP protocol port (typically 6666) for systems running the affected module. Configure firewall rules to limit inbound connections to this port only from trusted internal or management networks. A service reload or restart may be required for firewall changes to take full effect.