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CVE-2011-4317

MEDIUM severity · CVSS 4.3 · Improper input validation
4.3CVSS MEDIUM

Summary

The mod_proxy module in the Apache HTTP Server 1.3.x through 1.3.42, 2.0.x through 2.0.64, and 2.2.x through 2.2.21, when the Revision 1179239 patch is in place, does not properly interact with use of (1) RewriteRule and (2) ProxyPassMatch pattern matches for configuration of a reverse proxy, which allows remote attackers to send requests to intranet servers via a malformed URI containing an @ (at sign) character and a : (colon) character in invalid positions. NOTE: this vulnerability exists because of an incomplete fix for CVE-2011-3368.

Impact & exploitability

Attack vectorNetwork
Attack complexity
Privileges required
User interaction
Confidentiality impactNone
Integrity impact
Availability impactNone
Exploit probability (EPSS)78%

AV:N/AC:M/Au:N/C:N/I:P/A:N

Affected products we track (1)

Recommendation

Apply the vendor fix in your normal patch cycle. Open any affected product above for its exact safe version.

Last checked: Wed, 10 Jun 2026 22:18:30 UTC