dbcve.org
Mod PerlApplication · Apache

CVE-2011-2767

CRITICAL · 9.8 CVSS v3.0 Published 2018-08-26
Fix available
A fix is available. Upgrade to after 2.0.10 or later.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
mod_perl 2.0 through 2.0.10 allows attackers to execute arbitrary Perl code by placing it in a user-owned .htaccess file, because (contrary to the documentation) there is no configuration option that permits Perl code for the administrator's control of HTTP request processing without also permitting unprivileged users to run Perl code in the context of the user account that runs Apache HTTP Server processes.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

mod_perl 2.0 through 2.0.10 allows arbitrary Perl code execution via user-controlled .htaccess files. The vulnerability exists because there is no configuration option to enable Perl processing for administrator-controlled request handling without simultaneously permitting unprivileged users to execute Perl code in the Apache process context.

MitigationDisable mod_perl processing in user-accessible directories via configuration (Require directive or removing PerlOptions +ParseHeaders), or implement additional access controls at the application level to prevent untrusted .htaccess modifications.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Mod PerlApplication
Affected:>= 2.0.0, <= 2.0.10
Debian LinuxOperating system
Affected:= 8.0
Enterprise LinuxOperating system
Affected:= 6.0= 6.7= 7.0= 7.3= 7.4= 7.5= 7.6
Enterprise Linux DesktopOperating system
Affected:= 6.0
Enterprise Linux ServerOperating system
Affected:= 6.0
Enterprise Linux WorkstationOperating system
Affected:= 6.0
Ubuntu LinuxOperating system
Affected:= 12.04= 14.04= 16.04= 18.04= 18.10

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Confirm mod_perl is loaded in Apache
    Inspect Apache configuration files (httpd.conf, apache2.conf, or included config files) for the line 'LoadModule perl_module modules/mod_perl.so' or check with 'apache2ctl -M' or 'httpd -M' to list loaded modules
    Affected if mod_perl module is loaded in Apache
  2. Identify installed mod_perl version
    Run 'perl -MMOD_PERL -e "print $MOD_PERL::VERSION"' or check the mod_perl package version with your package manager (dpkg -l | grep mod_perl or rpm -qa | grep mod_perl)
    Affected if version is 2.0.0 through 2.0.10 inclusive
  3. Check if PerlOptions ParseHeaders is enabled
    Search Apache configuration for 'PerlOptions +ParseHeaders' or 'PerlOptions ParseHeaders' directive, which enables Perl processing in .htaccess context
    Affected if PerlOptions ParseHeaders is enabled in the configuration
  4. Verify .htaccess override permissions in user directories
    Check Apache configuration for Directory blocks pointing to user-accessible paths (e.g., /var/www, /home/*/public_html) and examine the AllowOverride directive; look for 'AllowOverride All' or 'AllowOverride PerlOptions' or 'AllowOverride Options=PerlOptions'
    Affected if AllowOverride permits Perl options or is set to All in directories where untrusted users can create or modify .htaccess files
  5. Confirm .htaccess files can contain Perl directives
    Examine .htaccess files in user-accessible directories for presence of mod_perl directives such as 'PerlOptions', 'PerlSetVar', 'PerlInitHandler', or 'SetHandler perl-script'
    Affected if .htaccess files in user directories contain mod_perl directives and those directories are accessible via Apache

You are affected if mod_perl version 2.0.0-2.0.10 is installed with PerlOptions enabled and user directories allow untrusted modification of .htaccess files containing Perl directives.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to a release after 2.0.10
Interim mitigation

Disable mod_perl processing in user-accessible directories via configuration (Require directive or removing PerlOptions +ParseHeaders), or implement additional access controls at the application level to prevent untrusted .htaccess modifications.

Recommended fix High confidence

mod_perl 2.0.11 or later

  1. 1. Check current mod_perl version: perl -MMOD_PERL -e 'print $MOD_PERL::VERSION' or check via httpd -v and apachectl -M 2>&1 | grep perl
  2. 2. For Debian/Ubuntu: Run 'apt-get update && apt-get upgrade libapache2-mod-perl2'
  3. 3. For RHEL/CentOS: Run 'yum update mod_perl'
  4. 4. For SUSE/openSUSE: Run 'zypper update mod_perl'
  5. 5. After upgrade, verify version is 2.0.11 or later: perl -MMOD_PERL -e 'print $MOD_PERL::VERSION'
  6. 6. Test Apache restart: systemctl restart apache2 or httpd
  7. 7. Review any .htaccess files in web directories and remove or disable Perl directives if not explicitly required
Caveat Minor: Upgrading mod_perl may require retesting custom Perl handlers and directives for compatibility with the newer version

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Mod Perl Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing6.0 h
  • Review / QA4.0 h
22.0 hours of engineering $3,860
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $6,176.

Scan for this in your stack

Free · runs locally
dbcve dependency scanner

Check whether your project pulls in CVE-2011-2767 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.

Get it on GitHub Scan in the browser

References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2011-2767 in production — separate from our analysis above.

No notes yet

Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.

What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data