CVE-2011-4317
MediumPublic exploitThe 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…
Published Nov 30, 2011 · Updated Aug 4, 2026 · Also known as DEBIAN-CVE-2011-4317
Key Facts
Patch immediately- CVE-2011-4317 is a medium-severity vulnerability (CVSS 4.3 v2) affecting HTTP Server (Apache), apache2 (debian), rootio-apache2 and 12 more products.
- It is not listed in any known-exploited vulnerabilities catalog. Public exploit code is available.
- EPSS estimates a 60% probability of exploitation in the next 30 days.
- Fixed versions are available, including apache2 2.2.16-6+squeeze6, apache2 2.2.21-3, apache2 2.2.9-10+lenny12.
- Brandefense priority: patch immediately, because it is very likely to be exploited soon.
CVSS v2
4.3
AV:N/AC:M/Au:N/C:N/I:P/A:N
EPSS (30-day exploit likelihood)
60%
Higher than 99.1% of all scored CVEs
Exploited in the wild
No known
Not in a known-exploited catalog
Public exploit code
Available
Proof-of-concept or weaponized module
Get the full CVE-2011-4317 brief as a PDF
Every affected product and fixed release, exploitation status and a first 24 hours response checklist, emailed within minutes.
Description
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.
Affected Products
127 affected entries in total| Product | Affected versions | Fixed in |
|---|---|---|
| HTTP ServerApache | 1.3, 1.3.0, 1.3.1, 1.3.10, 1.3.1.1, 1.3.11, 1.3.12, 1.3.13 | n/a |
| apache2debian | See advisory | 2.2.21-3 |
| rootio-apache2rootio | See advisory | 2.2.21-3 |
| httpd-develoracle | See advisory | 2.2.15-15.0.1.el6_2.1 |
| httpdoracle | See advisory | 2.2.15-15.0.1.el6_2.1 |
Patched Releases
apache2
2.2.16-6+squeeze6, 2.2.21-3, 2.2.9-10+lenny12, 2.4.23-4.1
apache2-devel
2.4.23-4.1
apache2-doc
2.4.23-4.1
apache2-event
2.4.23-4.1
apache2-example-pages
2.4.23-4.1
apache2-prefork
2.4.23-4.1
apache2-utils
2.4.23-4.1
apache2-worker
2.4.23-4.1
httpd
0:2.2.15-15.el6_2.1, 2.2.15-15.0.1.el6_2.1
httpd-devel
2.2.15-15.0.1.el6_2.1
httpd-manual
2.2.15-15.0.1.el6_2.1
httpd-tools
2.2.15-15.0.1.el6_2.1
mod_ssl
1:2.2.15-15.0.1.el6_2.1
rootio-apache2
2.2.21-3
Timeline
Publicly disclosed
Nov 30, 2011
Last updated
Aug 4, 2026
Weakness Type
- CWE-20 Improper Input Validation
References
- advisoryRHSA-2012:0128
- advisoryhttps://security-tracker.debian.org/tracker/CVE-2011-4317
- exploithttps://community.qualys.com/blogs/securitylabs/2011/11/23/apache-reverse-proxy-bypass-issue
- exploitExploitDB-36352
- exploithttp://thread.gmane.org/gmane.comp.apache.devel/46440
FAQ
Common Questions.
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 attac…
Affected: HTTP Server (Apache) versions 1.3, 1.3.0, 1.3.1, 1.3.10, 1.3.1.1, 1.3.11, 1.3.12, 1.3.13; apache2 (debian); rootio-apache2, among others. The full list is in the CVE brief.
It is not listed in any known-exploited vulnerabilities catalog.
No, it is not currently listed in the CISA Known Exploited Vulnerabilities catalog.
Public exploit code is available.
Fixed versions are available, including apache2 2.2.16-6+squeeze6, apache2 2.2.21-3, apache2 2.2.9-10+lenny12.
Brandefense priority: patch immediately, because it is very likely to be exploited soon.
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