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CVE-2011-3368: 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 does not properly…

MediumCVSS 5.0 · v2.0—Weaponized Fix available

Noroxi assessment

Priority: Plan (action score 47/100)

  • A ready-made attack module is public (Metasploit); exploiting it takes no special expertise.
  • Public proof-of-concept code exists (Exploit-DB, GitHub); there is no record of exploitation in the wild.
  • Probability of exploitation in the next 30 days: 90.7% (FIRST EPSS); higher than 99.8% of all records.
  • No special conditions are required; it is repeatable.
  • Fixed version: apache2 (Debian:12) 2.2.21-2; apache2 (Debian:5.0) 2.2.9-10+lenny12; apache2 (Debian:6.0) 2.2.16-6+squeeze6.

Add it to your regular patch cycle. Upgrade to apache2 (Debian:12) 2.2.21-2; apache2 (Debian:5.0) 2.2.9-10+lenny12; apache2 (Debian:6.0) 2.2.16-6+squeeze6 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

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 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 initial @ (at sign) character.

Published
Oct 5, 2011
Updated
Jun 16, 2026
EPSS
90.7% · 99th percentile

Report tools

JSON

Action score

47

Plan

Add it to your regular patch cycle.

CVSS
20 / 40 · 5.0 / 10
CISA KEV
0 / 30 · Not listed
EPSS
27 / 30 · 90.7%

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  • Not in KEV: no record of exploitation in the wild
  • Weaponized exploit exists
  • A fix has been released

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When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
apachehttp server

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When you'll hear from us

  • when a new CVE affecting this product is published
  • when a record in your stack enters KEV or is weaponized

One daily email digest (06:00 UTC); connect a webhook for KEV listings and weaponized exploits every 10 minutes on paid plans, on the hour on the free plan.

Is Apache HTTP Server on your server exposed to the internet?Run a port scan

Your free account also gets you

  • CVE alerts: add the products and versions you run, get the new CVEs that affect them
  • Uptime monitoring: 1 site, instant email when it goes down
  • Add your domain: subdomains and takeover risk scanned every week (1 domain)
  • 10 scans an hour on the security tools, at most 30 a day (3 a day without an account), an API key and MCP
  • All your scans in one panel: findings, what changed in the last scan, a report per domain or per client (PDF, share link)
All free tools

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Free account, no card. Unfollow any time.

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Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • apache http server1.3
  • apache http server1.3.0
  • apache http server1.3.1
  • apache http server1.3.1.1
  • apache http server1.3.10
  • apache http server1.3.11
  • apache http server1.3.12
  • apache http server1.3.13
+12 more rows
  • apache http server1.3.14
  • apache http server1.3.15
  • apache http server1.3.16
  • apache http server1.3.17
  • apache http server1.3.18
  • apache http server1.3.19
  • apache http server1.3.2
  • apache http server1.3.20
  • apache http server1.3.22
  • apache http server1.3.23
  • apache http server1.3.24
  • apache http server1.3.25

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Debian:12apache2before 2.2.21-22.2.21-2
Debian:5.0apache2before 2.2.9-10+lenny122.2.9-10+lenny12
Debian:6.0apache2before 2.2.16-6+squeeze62.2.16-6+squeeze6
Red Hat:enterprise_linux:4::ashttpdbefore 0:2.0.52-49.ent0:2.0.52-49.ent
Red Hat:enterprise_linux:4::ashttpd-debuginfobefore 0:2.0.52-49.ent0:2.0.52-49.ent
Red Hat:enterprise_linux:4::ashttpd-develbefore 0:2.0.52-49.ent0:2.0.52-49.ent
Red Hat:enterprise_linux:4::ashttpd-manualbefore 0:2.0.52-49.ent0:2.0.52-49.ent
Red Hat:enterprise_linux:4::ashttpd-suexecbefore 0:2.0.52-49.ent0:2.0.52-49.ent
Red Hat:enterprise_linux:4::asmod_sslbefore 1:2.0.52-49.ent1:2.0.52-49.ent
Red Hat:enterprise_linux:5::clienthttpdbefore 0:2.2.3-53.el5_7.30:2.2.3-53.el5_7.3
Red Hat:enterprise_linux:5::clienthttpd-debuginfobefore 0:2.2.3-53.el5_7.30:2.2.3-53.el5_7.3
Red Hat:enterprise_linux:5::clientmod_sslbefore 1:2.2.3-53.el5_7.31:2.2.3-53.el5_7.3
Red Hat:enterprise_linux:5::client_workstationhttpd-develbefore 0:2.2.3-53.el5_7.30:2.2.3-53.el5_7.3
Red Hat:enterprise_linux:5::client_workstationhttpd-manualbefore 0:2.2.3-53.el5_7.30:2.2.3-53.el5_7.3
Red Hat:enterprise_linux:6::serverhttpdbefore 0:2.2.15-9.el6_1.30:2.2.15-9.el6_1.3
Red Hat:enterprise_linux:6::serverhttpd-debuginfobefore 0:2.2.15-9.el6_1.30:2.2.15-9.el6_1.3
Red Hat:enterprise_linux:6::serverhttpd-develbefore 0:2.2.15-9.el6_1.30:2.2.15-9.el6_1.3
Red Hat:enterprise_linux:6::serverhttpd-manualbefore 0:2.2.15-9.el6_1.30:2.2.15-9.el6_1.3
Red Hat:enterprise_linux:6::serverhttpd-toolsbefore 0:2.2.15-9.el6_1.30:2.2.15-9.el6_1.3
Red Hat:enterprise_linux:6::servermod_sslbefore 1:2.2.15-9.el6_1.31:2.2.15-9.el6_1.3
Red Hat:jboss_enterprise_web_server:1::el5httpdbefore 0:2.2.17-15.4.ep5.el50:2.2.17-15.4.ep5.el5
Red Hat:jboss_enterprise_web_server:1::el5httpd-develbefore 0:2.2.17-15.4.ep5.el50:2.2.17-15.4.ep5.el5
Red Hat:jboss_enterprise_web_server:1::el5httpd-manualbefore 0:2.2.17-15.4.ep5.el50:2.2.17-15.4.ep5.el5
Red Hat:jboss_enterprise_web_server:1::el5mod_sslbefore 1:2.2.17-15.4.ep5.el51:2.2.17-15.4.ep5.el5

+5

Same product

apache: all records

Other highest-scoring records for the same primary product.

  • CVE-2021-42013Path Traversal and Remote Code Execution in Apache HTTP Server 2.4.49 and 2.4.50 (incomplete fix of CVE-2021-41773)KEV
    99Now
  • CVE-2021-41773Path traversal and file disclosure vulnerability in Apache HTTP Server 2.4.49KEV
    99Now
  • CVE-2024-38475Apache HTTP Server weakness in mod_rewrite when first segment of substitution matches filesystem path.KEV
    96Now

Published before and after this one in the same product

  • ← EarlierCVE-2011-3192Aug 29, 2011 · The byterange filter in the Apache HTTP Server 1.3.x, 2.0.x through 2.0.64, and 2.2.x through 2.2.19 allows remote attackers to cause a…
    61This week
  • ← EarlierCVE-2011-3348Sep 20, 2011 · The mod_proxy_ajp module in the Apache HTTP Server before 2.2.21, when used with mod_proxy_balancer in certain configurations, allows…
    24Monitor
  • Later →CVE-2011-3607Nov 8, 2011 · Integer overflow in the ap_pregsub function in server/util.c in the Apache HTTP Server 2.0.x through 2.0.64 and 2.2.x through 2.2.21, when…
    18Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
debian:apache22.2.21-2 · Debian:12Package registry (OSV)
red hat:httpd0:2.2.15-9.el6_1.3 · Red Hat:enterprise_linux:6::serverPackage registry (OSV)
red hat:httpd-debuginfo0:2.2.15-9.el6_1.3 · Red Hat:enterprise_linux:6::serverPackage registry (OSV)
red hat:httpd-devel0:2.2.15-9.el6_1.3 · Red Hat:enterprise_linux:6::serverPackage registry (OSV)
red hat:httpd-manual0:2.2.15-9.el6_1.3 · Red Hat:enterprise_linux:6::serverPackage registry (OSV)
red hat:httpd-suexec0:2.0.52-49.ent · Red Hat:enterprise_linux:4::asPackage registry (OSV)
red hat:httpd-tools0:2.2.15-9.el6_1.3 · Red Hat:enterprise_linux:6::serverPackage registry (OSV)
red hat:mod_ssl1:2.2.15-9.el6_1.3 · Red Hat:enterprise_linux:6::serverPackage registry (OSV)

Exploit status

Weaponized

A ready exploit tool or active in-the-wild use is known for this vulnerability. This should be your top priority.

Evidence

  • Metasploit module ×1
  • Exploit-DB entry ×1
  • Proof-of-concept repository on GitHub ×2

Noroxi does not host or link to exploit code. Metasploit module names and Nuclei template ids are shown (names, not code); Exploit-DB entries and PoC repositories are given as counts only.

Public exploit evidence
SourceKindDate
Exploit-DB entryremote2011-10-11
Metasploit moduleauxiliary/scanner/http/rewrite_proxy_bypassApache Reverse Proxy Bypass Vulnerability Scannerauxiliary—
Proof-of-concept repository on GitHubstars:12017-04-18
Proof-of-concept repository on GitHubstars:02019-03-22

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

  1. Published
  2. First PoC+5 d
  3. TodayNov 15, 2026+5520 d

Not on record for this CVE: EPSS history · patch commit or PR link · researcher credit · variant or chain candidate · public bounty program.

Technical details

Attack conditions

  • No special conditions are required; it is repeatable.

If successful

Confidentiality
P · data can be read
Integrity
none
Availability
none
Attack complexity
Low
Confidentiality impact
P
Integrity impact
None
Availability impact
None

Weakness class (CWE)

CWE-20 · Improper Input Validation

CVSS vector

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

nvd-primary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

References

Show all references (19 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records