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CVE-2011-3607: 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…

MediumCVSS 4.4 · v2.0—Proof of concept Fix available

Noroxi assessment

Priority: Monitor (action score 18/100)

  • Public proof-of-concept code exists (Exploit-DB); there is no record of exploitation in the wild.
  • Probability of exploitation in the next 30 days: 4.9% (FIRST EPSS); higher than 92.2% of all records.
  • Fixed version: apache2 (Debian:12) 2.2.21-4; apache2 (Debian:5.0) 2.2.9-10+lenny12; apache2 (Debian:6.0) 2.2.16-6+squeeze6.

Low priority for now. Upgrade to apache2 (Debian:12) 2.2.21-4; 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

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 the mod_setenvif module is enabled, allows local users to gain privileges via a .htaccess file with a crafted SetEnvIf directive, in conjunction with a crafted HTTP request header, leading to a heap-based buffer overflow.

Published
Nov 8, 2011
Updated
Jun 16, 2026
EPSS
4.9% · 92th percentile

Report tools

JSON

Action score

18

Monitor

Low priority for now.

CVSS
17 / 40 · 4.4 / 10
CISA KEV
0 / 30 · Not listed
EPSS
1 / 30 · 4.9%

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  • Not in KEV: no record of exploitation in the wild
  • Proof of concept exists, no weaponized module
  • 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

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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.

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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
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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 server2.0
  • apache http server2.0.28
  • apache http server2.0.32
  • apache http server2.0.34
  • apache http server2.0.35
  • apache http server2.0.36
  • apache http server2.0.37
  • apache http server2.0.38
+12 more rows
  • apache http server2.0.39
  • apache http server2.0.40
  • apache http server2.0.41
  • apache http server2.0.42
  • apache http server2.0.43
  • apache http server2.0.44
  • apache http server2.0.45
  • apache http server2.0.46
  • apache http server2.0.47
  • apache http server2.0.48
  • apache http server2.0.49
  • apache http server2.0.50

Package-level exposure

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

EcosystemPackageAffected rangeFix
Debian:12apache2before 2.2.21-42.2.21-4
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:5::clienthttpdbefore 0:2.2.3-63.el5_8.10:2.2.3-63.el5_8.1
Red Hat:enterprise_linux:5::clienthttpd-debuginfobefore 0:2.2.3-63.el5_8.10:2.2.3-63.el5_8.1
Red Hat:enterprise_linux:5::clientmod_sslbefore 1:2.2.3-63.el5_8.11:2.2.3-63.el5_8.1
Red Hat:enterprise_linux:5::client_workstationhttpd-develbefore 0:2.2.3-63.el5_8.10:2.2.3-63.el5_8.1
Red Hat:enterprise_linux:5::client_workstationhttpd-manualbefore 0:2.2.3-63.el5_8.10:2.2.3-63.el5_8.1
Red Hat:enterprise_linux:6::clienthttpdbefore 0:2.2.15-15.el6_2.10:2.2.15-15.el6_2.1
Red Hat:enterprise_linux:6::clienthttpd-debuginfobefore 0:2.2.15-15.el6_2.10:2.2.15-15.el6_2.1
Red Hat:enterprise_linux:6::clienthttpd-develbefore 0:2.2.15-15.el6_2.10:2.2.15-15.el6_2.1
Red Hat:enterprise_linux:6::clienthttpd-manualbefore 0:2.2.15-15.el6_2.10:2.2.15-15.el6_2.1
Red Hat:enterprise_linux:6::clienthttpd-toolsbefore 0:2.2.15-15.el6_2.10:2.2.15-15.el6_2.1
Red Hat:enterprise_linux:6::clientmod_sslbefore 1:2.2.15-15.el6_2.11:2.2.15-15.el6_2.1
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
Red Hat:jboss_enterprise_web_server:1::el6httpdbefore 0:2.2.17-15.4.ep5.el60:2.2.17-15.4.ep5.el6
Red Hat:jboss_enterprise_web_server:1::el6httpd-develbefore 0:2.2.17-15.4.ep5.el60:2.2.17-15.4.ep5.el6
Red Hat:jboss_enterprise_web_server:1::el6httpd-manualbefore 0:2.2.17-15.4.ep5.el60:2.2.17-15.4.ep5.el6
Red Hat:jboss_enterprise_web_server:1::el6httpd-toolsbefore 0:2.2.17-15.4.ep5.el60:2.2.17-15.4.ep5.el6
Red Hat:jboss_enterprise_web_server:1::el6mod_sslbefore 1:2.2.17-15.4.ep5.el61:2.2.17-15.4.ep5.el6

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-2011-3348Sep 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
  • ← EarlierCVE-2011-3368Oct 5, 2011 · 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…
    47Plan
  • Later →CVE-2011-4415Nov 8, 2011 · 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 the mod_setenvif…
    5Monitor

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:apache22.2.21-4 · Debian:12Package registry (OSV)
red hat:httpd0:2.2.15-15.el6_2.1 · Red Hat:enterprise_linux:6::clientPackage registry (OSV)
red hat:httpd-debuginfo0:2.2.15-15.el6_2.1 · Red Hat:enterprise_linux:6::clientPackage registry (OSV)
red hat:httpd-devel0:2.2.15-15.el6_2.1 · Red Hat:enterprise_linux:6::clientPackage registry (OSV)
red hat:httpd-manual0:2.2.15-15.el6_2.1 · Red Hat:enterprise_linux:6::clientPackage registry (OSV)
red hat:httpd-tools0:2.2.15-15.el6_2.1 · Red Hat:enterprise_linux:6::clientPackage registry (OSV)
red hat:mod_ssl1:2.2.15-15.el6_2.1 · Red Hat:enterprise_linux:6::clientPackage registry (OSV)

Exploit status

Proof of concept available

A public proof of concept or detection signature exists. Exploit knowledge is out there; don't delay patching.

Evidence

  • Exploit-DB entry ×1

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 entrydos2011-11-02

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. First PoC-6 d
  2. Published
  3. TodayNov 15, 2026+5486 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

    If successful

    Confidentiality
    P · data can be read
    Integrity
    P · data or configuration can be modified
    Availability
    P · the service can be disrupted
    Attack complexity
    M
    Confidentiality impact
    P
    Integrity impact
    P
    Availability impact
    P

    Weakness class (CWE)

    CWE-189 · Numeric Errors

    CVSS vector

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

    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.

    MITRE has no CAPEC/ATT&CK mapping for this CWE.

    References

    Show all references (19 more)

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

    All records