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.
CVE-2011-3368
“—” beside the score: it is equal to NVD's CVSS v2 base score.
This CVE was only ever scored under CVSS v2.0. NVD CVSS v2.0 base 5.0 — NVD rates that MEDIUM (NVD's v2 bands: LOW 0.0–3.9 / MEDIUM 4.0–6.9 / HIGH 7.0–10.0; no CRITICAL band). Vector AV:N/AC:L/Au:N/C:P/I:N/A:N. CVSS v2 is an older, coarser metric than v3.1/v4.0 (no Scope, no User Interaction, no Attack Requirements), so it is not directly comparable to a v3 or v4 score. NVD has never re-scored this record under v3. EPSS predicts 91% exploitation probability in the next 30 days; it does not lift the v2 base. EPSS sets EG Risk's exploitation input. Confidence: LOW.
- 101 internet-facing services (distinct ip:port) on record running an affected version — derived from Shodan data (© Shodan); a patched service can stay counted while its port stays open
- High exploitation likelihood — EPSS 91%
- Public exploit code is available (Metasploit, Exploit-DB, marked verified by Exploit-DB)
A fix is available — apply it.
101 internet-facing services (distinct ip:port) on record running a version that maps to CVE-2011-3368, in our KEV-Exposure radar’s Shodan-derived sample.
How it counts: every 12 hours, when Shodan query credits allow, the radar runs one Shodan query per tracked product, reads up to 100 ip:port services per query, and keeps a service when its banner version matches a CISA-KEV or high-EPSS CVE; a service is dropped when neither a search nor a Shodan InternetDB port re-check has refreshed it for 21 days. A re-check that finds the port still listed by Shodan InternetDB refreshes the service without re-reading the banner, so a patched service can stay counted while its port stays open. A count is a banner-version inference over a sample, not an exploit test and not an internet-wide census, and the unit is a service, not a machine: a machine answering on two ports counts twice.
- CVSS v2.0 (legacy)
- 5.0MEDIUMNVD never assigned a CVSS v3 rating to this CVE
- EG Score
- 5.0MEDIUMlow confidence
- EG Risk
- 59EG Risk 59/100
EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).
How it’s computed (value × EchelonGraph’s weight)Severity50% × 45%The EG Score, 5.0 of 10.Exploitation91% × 40%FIRST EPSS: the 30-day exploitation probability when EchelonGraph scored this CVE.Automatability0% × 15%CISA's BOD 26-04 default: no one has published Automatable for this CVE, and CISA treats it as “no” for a CVE not in KEV.SSVC (CISA's decision table, applied by EchelonGraph): Track at low, Track* at medium and Attend at high mission impact.Exploitation public PoC (exploit code on record) · Automatable no (CISA's BOD 26-04 default) · Technical impact total (CISA's BOD 26-04 default). EchelonGraph holds no SSVC assessment of this CVE from CISA: none of these inputs is from Vulnrichment. EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE.Action: A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high. - EPSS PROB
- 91%
- EPSS %ILE
- 99th
- KEV
- Not listed
SSVC (CISA's decision table, applied by EchelonGraph)Track at low, Track* at medium and Attend at high mission impact.
A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.
Exploitation public PoC (exploit code on record) · Automatable no (CISA's BOD 26-04 default) · Technical impact total (CISA's BOD 26-04 default). EchelonGraph holds no SSVC assessment of this CVE from CISA: none of these inputs is from Vulnrichment. EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table
BOD 26-04 (CISA's remediation timeline, Table 1)14 days if the affected system is publicly exposed; Fix on system upgrade if it is not.
In CISA KEV no (CISA's KEV catalog) · Automatable no (CISA's BOD 26-04 default) · Technical impact total (CISA's BOD 26-04 default). Where an input reads “CISA's BOD 26-04 default”, no one has published it for this CVE, and CISA's implementation guidance says: “If “Automatable” and “Technical Impact” information items about a CVE ID are not available and the CVE ID is not in the KEV Catalog, CISA will treat its values as “no” and “total,” respectively, until CISA or a third party provides metadata about the CVE ID. CISA will always provide the Vulnrichment data for a CVE ID listed in the KEV Catalog.” Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it
Published
October 5, 2011
Last Modified
April 29, 2026
References (55)
- secalert@redhat · CVE Programhttp://kb.juniper.net/JSA10585
- secalert@redhat · CVE Programhttp://lists.apple.com/archives/security-announce/2012/Sep/msg00004.html
- secalert@redhat · CVE Programhttp://lists.opensuse.org/opensuse-security-announce/2011-11/msg00011.html
- secalert@redhat · CVE Programhttp://lists.opensuse.org/opensuse-updates/2013-02/msg00009.html
- secalert@redhat · CVE Programhttp://lists.opensuse.org/opensuse-updates/2013-02/msg00012.html
- secalert@redhat · CVE Programhttp://marc.info/?l=bugtraq&m=133294460209056&w=2
- secalert@redhat · CVE Programhttp://marc.info/?l=bugtraq&m=134987041210674&w=2
- secalert@redhat · CVE Programhttp://osvdb.org/76079 (archived copy: the site no longer serves it)
- secalert@redhat · CVE Programhttp://rhn.redhat.com/errata/RHSA-2012-0542.html
- secalert@redhat · CVE Programhttp://rhn.redhat.com/errata/RHSA-2012-0543.html
- secalert@redhat · CVE Programhttp://seclists.org/fulldisclosure/2011/Oct/232
- secalert@redhat · CVE Programhttp://seclists.org/fulldisclosure/2011/Oct/273
- secalert@redhat · CVE Programhttp://secunia.com/advisories/46288 (archived copy: the site no longer serves it)
- secalert@redhat · CVE Programhttp://secunia.com/advisories/46414 (archived copy: the site no longer serves it)
- secalert@redhat · CVE Programhttp://secunia.com/advisories/48551 (archived copy: the site no longer serves it)
15 of 55 shown · show the other 40
- secalert@redhat · CVE Programhttp://support.apple.com/kb/HT5501
- secalert@redhat · CVE Programhttp://svn.apache.org/viewvc?view=revision&revision=1179239Patch
- secalert@redhat · CVE Programhttp://web.archiveorange.com/archive/v/ZyS0hzECD5zzb2NkvQltExploit · Patch
- secalert@redhat · CVE Programhttp://www-01.ibm.com/support/docview.wss?uid=nas2064c7e5f53452ff686257927003c8d42
- secalert@redhat · CVE Programhttp://www-01.ibm.com/support/docview.wss?uid=nas2b7c57b1f1035675186257927003c8d48
- secalert@redhat · CVE Programhttp://www.contextis.com/research/blog/reverseproxybypass/
- secalert@redhat · CVE Programhttp://www.debian.org/security/2012/dsa-2405
- secalert@redhat · CVE Programhttp://www.exploit-db.com/exploits/17969
- secalert@redhat · CVE Programhttp://www.mandriva.com/security/advisories?name=MDVSA-2011:144
- secalert@redhat · CVE Programhttp://www.mandriva.com/security/advisories?name=MDVSA-2013:150
- secalert@redhat · CVE Programhttp://www.oracle.com/technetwork/topics/security/cpujan2015-1972971.html
- secalert@redhat · CVE Programhttp://www.oracle.com/technetwork/topics/security/cpujul2012-392727.html
- secalert@redhat · CVE Programhttp://www.redhat.com/support/errata/RHSA-2011-1391.html
- secalert@redhat · CVE Programhttp://www.redhat.com/support/errata/RHSA-2011-1392.html
- secalert@redhat · CVE Programhttp://www.securityfocus.com/bid/49957 (archived copy: the site no longer serves it)
- secalert@redhat · CVE Programhttp://www.securitytracker.com/id?1026144
- secalert@redhat · CVE Programhttps://bugzilla.redhat.com/show_bug.cgi?id=740045Exploit · Patch
- secalert@redhat · CVE Programhttps://exchange.xforce.ibmcloud.com/vulnerabilities/70336
- secalert@redhat · CVE Programhttps://lists.apache.org/thread.html/54a42d4b01968df1117cea77fc53d6beb931c0e05936ad02af93e9ac%40%3Ccvs.httpd.apache.org%3E
- secalert@redhat · CVE Programhttps://lists.apache.org/thread.html/5df9bfb86a3b054bb985a45ff9250b0332c9ecc181eec232489e7f79%40%3Ccvs.httpd.apache.org%3E
- secalert@redhat · CVE Programhttps://lists.apache.org/thread.html/8d63cb8e9100f28a99429b4328e4e7cebce861d5772ac9863ba2ae6f%40%3Ccvs.httpd.apache.org%3E
- secalert@redhat · CVE Programhttps://lists.apache.org/thread.html/f7f95ac1cd9895db2714fa3ebaa0b94d0c6df360f742a40951384a53%40%3Ccvs.httpd.apache.org%3E
- secalert@redhat · CVE Programhttps://lists.apache.org/thread.html/r0276683d8e1e07153fc8642618830ac0ade85b9ae0dc7b07f63bb8fc%40%3Ccvs.httpd.apache.org%3E
- secalert@redhat · CVE Programhttps://lists.apache.org/thread.html/r064df0985779b7ee044d3120d71ba59750427cf53f57ba3384e3773f%40%3Ccvs.httpd.apache.org%3E
- secalert@redhat · CVE Programhttps://lists.apache.org/thread.html/r1d201e3da31a2c8aa870c8314623caef7debd74a13d0f25205e26f15%40%3Ccvs.httpd.apache.org%3E
- secalert@redhat · CVE Programhttps://lists.apache.org/thread.html/r2cb985de917e7da0848c440535f65a247754db8b2154a10089e4247b%40%3Ccvs.httpd.apache.org%3E
- secalert@redhat · CVE Programhttps://lists.apache.org/thread.html/r5419c9ba0951ef73a655362403d12bb8d10fab38274deb3f005816f5%40%3Ccvs.httpd.apache.org%3E
- secalert@redhat · CVE Programhttps://lists.apache.org/thread.html/r57608dc51b79102f3952ae06f54d5277b649c86d6533dcd6a7d201f7%40%3Ccvs.httpd.apache.org%3E
- secalert@redhat · CVE Programhttps://lists.apache.org/thread.html/r5f9c22f9c28adbd9f00556059edc7b03a5d5bb71d4bb80257c0d34e4%40%3Ccvs.httpd.apache.org%3E
- secalert@redhat · CVE Programhttps://lists.apache.org/thread.html/r688df6f16f141e966a0a47f817e559312b3da27886f59116a94b273d%40%3Ccvs.httpd.apache.org%3E
- secalert@redhat · CVE Programhttps://lists.apache.org/thread.html/r75cbe9ea3e2114e4271bbeca7aff96117b50c1b6eb7c4772b0337c1f%40%3Ccvs.httpd.apache.org%3E
- secalert@redhat · CVE Programhttps://lists.apache.org/thread.html/r8828e649175df56f1f9e3919938ac7826128525426e2748f0ab62feb%40%3Ccvs.httpd.apache.org%3E
- secalert@redhat · CVE Programhttps://lists.apache.org/thread.html/r9e8622254184645bc963a1d47c5d47f6d5a36d6f080d8d2c43b2b142%40%3Ccvs.httpd.apache.org%3E
- secalert@redhat · CVE Programhttps://lists.apache.org/thread.html/r9ea3538f229874c80a10af473856a81fbf5f694cd7f471cc679ba70b%40%3Ccvs.httpd.apache.org%3E
- secalert@redhat · CVE Programhttps://lists.apache.org/thread.html/r9f93cf6dde308d42a9c807784e8102600d0397f5f834890708bf6920%40%3Ccvs.httpd.apache.org%3E
- secalert@redhat · CVE Programhttps://lists.apache.org/thread.html/rb9c9f42dafa25d2f669dac2a536a03f2575bc5ec1be6f480618aee10%40%3Ccvs.httpd.apache.org%3E
- secalert@redhat · CVE Programhttps://lists.apache.org/thread.html/rdca61ae990660bacb682295f2a09d34612b7bb5f457577fe17f4d064%40%3Ccvs.httpd.apache.org%3E
- secalert@redhat · CVE Programhttps://lists.apache.org/thread.html/re2e23465bbdb17ffe109d21b4f192e6b58221cd7aa8797d530b4cd75%40%3Ccvs.httpd.apache.org%3E
- secalert@redhat · CVE Programhttps://lists.apache.org/thread.html/rf6449464fd8b7437704c55f88361b66f12d5b5f90bcce66af4be4ba9%40%3Ccvs.httpd.apache.org%3E
- secalert@redhat · CVE Programhttps://lists.apache.org/thread.html/rfbaf647d52c1cb843e726a0933f156366a806cead84fbd430951591b%40%3Ccvs.httpd.apache.org%3E
Patch Availability(5)
| Vendor / Ecosystem | Fix (by version range) / Patch | Released | Source |
|---|---|---|---|
| ubuntu | apache2.2-bin (2.2.17-1ubuntu1.4) @ natty | 2026-07-23 | ubuntu |
| redhat | patch | 2012-05-07 | redhat |
| redhat | httpd-0:2.2.17-15.4.ep5.el6 | 2012-05-07 | redhat |
| redhat | httpd-0:2.2.3-53.el5_7.3 | 2011-10-20 | redhat |
| redhat | httpd-0:2.2.15-9.el6_1.3 | 2011-10-20 | redhat |
Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.
Affected Packages
(6 across 6 ecosystems)
Debian:11(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| apache2 | — |
| — |
Debian:12(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| apache2 | — |
| — |
Debian:13(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| apache2 | — |
| — |
Debian:14(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| apache2 | — |
| — |
Debian:5.0(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| apache2 | 2.2.9-10+lenny10 ... 2.2.9-10+lenny9 (10 versions) |
| — |
Debian:6.0(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| apache2 | 2.2.16-6 ... 2.2.16-6+squeeze4~bpo50+1 (8 versions) |
| — |
Weakness Classification(1)
MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.
All Vendor Advisories
(5)
Every vendor that published an advisory referencing this CVE — pulled from our cve_vendor_advisories aggregation. Click any row for the vendor's original advisory page.
- Red HatRHSA-2011:1391MODERATE2011-10-05
RHSA-2011:1391 — Moderate
- Red HatRHSA-2011:1392MODERATE2011-10-05
RHSA-2011:1392 — Moderate
- Red HatRHSA-2012:0542MODERATE2011-10-05
RHSA-2012:0542 — Moderate
- Red HatRHSA-2012:0543MODERATE2011-10-05
RHSA-2012:0543 — Moderate
- UbuntuUSN-1259-1MEDIUM
Apache vulnerabilities
Data Freshness Timeline
(refreshed 2× in last 7d / 6× in last 30d)
Each row is a time one of our pipelines fetched, updated or re-scored this CVE. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. An arrow marks a change the record states ("CVSS v3 → 9.1"); EPSS and GHSA rows show the values recorded at that time, not what changed (EPSS values are rounded; hover one for the exact figures). Most recent first.
A repeat, a row identical to one the same pipeline wrote less than 10 seconds earlier, is not a separate refresh and is not counted. 22 repeat rows among the latest 80 are merged into the row they repeat.
- 2026-10-12 01:41 UTCEG score recompute
- 2026-10-06 15:10 UTCEPSS rescoreEPSS 91% · 99th percentile
- 2026-10-01 02:40 UTCOSV refresh
- 2026-09-30 14:58 UTCEPSS rescoreEPSS 91% · 99th percentile
- 2026-09-29 08:21 UTCEG score recompute
- 2026-09-24 13:57 UTCEPSS rescoreEPSS 91% · 99th percentile
- 2026-09-12 05:53 UTCOSV refresh
- 2026-09-06 13:41 UTCEPSS rescoreEPSS 91% · 99th percentile
- 2026-09-05 15:22 UTCEPSS rescoreEPSS 91% · 99th percentile
- 2026-08-24 11:42 UTCOSV refresh
- 2026-08-19 16:58 UTCEPSS rescoreEPSS 91% · 99th percentile
- 2026-08-18 13:42 UTCEPSS rescoreEPSS 91% · 99th percentile
- 2026-08-15 01:25 UTCEPSS rescoreEPSS 91% · 99th percentile
- 2026-08-08 16:31 UTCEPSS rescoreEPSS 91% · 99th percentile
- 2026-08-08 07:49 UTCOSV refresh
- 2026-08-06 13:41 UTCEPSS rescoreEPSS 91% · 99th percentile
- 2026-08-05 19:12 UTCEPSS rescoreEPSS 91% · 99th percentile
- 2026-07-26 13:43 UTCEG score recomputeAssessed again: 5.0 MEDIUM
- 2026-07-23 01:06 UTCVendor advisory
- 2026-07-23 01:06 UTCGHSA enrichmentGHSA-j85c-9w9v-p2p3
- 2026-07-23 01:05 UTCEG score recompute▼ 9.00
- 2026-07-23 00:09 UTCEG score recompute
- 2026-07-22 21:35 UTCEG score recomputeFirst assessed: 9.0 CRITICAL
- 2026-07-22 21:35 UTCVendor advisory
- 2026-07-22 21:35 UTCGHSA enrichmentGHSA-j85c-9w9v-p2p3
Show 33 moreShow fewer
- 2026-07-22 14:03 UTCEPSS rescoreEPSS 91% · 99th percentile
- 2026-07-21 15:21 UTCEPSS rescoreEPSS 91% · 99th percentile
- 2026-07-20 17:03 UTCEPSS rescoreEPSS 91% · 99th percentile
- 2026-07-11 08:22 UTCEPSS rescoreEPSS 91% · 99th percentile
- 2026-07-05 18:29 UTCOSV refresh
- 2026-06-30 23:19 UTCEPSS rescoreEPSS 91% · 99th percentile
- 2026-06-25 13:46 UTCEPSS rescoreEPSS 91% · 99th percentile
- 2026-06-23 21:30 UTCEPSS rescoreEPSS 91% · 99th percentile
- 2026-06-17 17:49 UTCEPSS rescoreEPSS 91% · 99th percentile
- 2026-06-17 05:35 UTCOSV refresh
- 2026-06-15 17:44 UTCEPSS rescoreEPSS 91% · 99th percentile
- 2026-06-14 23:14 UTCEPSS rescoreEPSS 74% · 98th percentile
- 2026-06-13 22:57 UTCEPSS rescoreEPSS 73% · 98th percentile
- 2026-06-12 23:08 UTCEPSS rescoreEPSS 77% · 98th percentile
- 2026-06-11 13:56 UTCEPSS rescoreEPSS 77% · 98th percentile
- 2026-06-10 22:14 UTCEPSS rescoreEPSS 77% · 98th percentile
- 2026-06-08 14:14 UTCEPSS rescoreEPSS 77% · 98th percentile
- 2026-06-07 15:22 UTCEPSS rescoreEPSS 77% · 98th percentile
- 2026-06-06 13:44 UTCEPSS rescoreEPSS 77% · 98th percentile
- 2026-06-05 22:44 UTCEPSS rescoreEPSS 77% · 98th percentile
- 2026-06-05 06:07 UTCEPSS rescoreEPSS 77% · 98th percentile
- 2026-06-02 20:10 UTCEPSS rescoreEPSS 77% · 98th percentile
- 2026-06-01 13:49 UTCEPSS rescoreEPSS 77% · 98th percentile
- 2026-05-31 00:14 UTCEPSS rescoreEPSS 77% · 98th percentile
- 2026-05-29 13:40 UTCEPSS rescoreEPSS 77% · 98th percentile
- 2026-05-29 06:45 UTCEG score recompute
- 2026-05-29 06:45 UTCVendor advisory
- 2026-05-29 06:44 UTCGHSA enrichmentGHSA-j85c-9w9v-p2p3
- 2026-05-28 13:42 UTCEPSS rescoreEPSS 77% · 98th percentile
- 2026-05-26 07:16 UTCEPSS rescoreEPSS 77% · 98th percentile
- 2026-05-23 22:05 UTCOSV refresh
- 2026-05-22 21:15 UTCEPSS rescoreEPSS 77% · 98th percentile
- 2026-05-18 21:29 UTCEPSS rescoreEPSS 77% · 98th percentile
Publicly available exploits
(2 references)Public exploit code is referenced for this CVE (1 Metasploit module, 1 Exploit-DB entry). Defenders should treat patch urgency accordingly.
- Exploit-DBEDB-17969✓ verifiedPublished Oct 11, 2011
Apache mod_proxy - Reverse Proxy Exposure
Open source ↗ - Metasploitauxiliary/scanner/http/rewrite_proxy_bypass✓ verifiedPublished Oct 10, 2011
Apache Reverse Proxy Bypass Vulnerability Scanner
Open source ↗
Related CVEs(same product + same vendor + same CWE)
Same product
10 shownDebian:5.0:apache2
- CVE-2011-3192EG 7.8EPSS p100HIGH
- CVE-2012-0031EG 4.6MEDIUM
- CVE-2011-3607EG 4.4EPSS p92MEDIUM
- CVE-2012-0053EG 4.3EPSS p100MEDIUM
- CVE-2011-4317EG 4.3EPSS p99MEDIUM
- CVE-2011-3639EG 4.3EPSS p99MEDIUM
- CVE-2009-3555EG 9.8EPSS p100CRITICAL
- CVE-2009-1891EG 7.1EPSS p97HIGH
- CVE-2009-1890EG 7.1EPSS p97HIGH
- CVE-2010-0408EG 5.0EPSS p98MEDIUM
Same vendor
6 shownredhat:RHSA-2011:1391 · redhat:RHSA-2012:0542 · ubuntu:USN-1259-1
Frequently asked(4)
What is CVE-2011-3368?
When was CVE-2011-3368 made public?
Is CVE-2011-3368 actively exploited?
How do I remediate CVE-2011-3368?
Dependency Blast Radius
See which npm, PyPI, Go, and Maven packages are affected by CVE-2011-3368
Is Your Infrastructure Affected by CVE-2011-3368?
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