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Code InjectionWeakness · CWE-94

CVE-1999-0509

HIGH · 10.0 CVSS v2.0 Published 1996-05-29
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
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
Perl, sh, csh, or other shell interpreters are installed in the cgi-bin directory on a WWW site, which allows remote attackers to execute arbitrary commands.

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

Shell interpreters (Perl, sh, csh, or similar) are present in the cgi-bin directory of a web server, allowing remote attackers to directly invoke these interpreters via HTTP requests and execute arbitrary commands on the system with the web server's privileges.

MitigationRemove all shell interpreters and unnecessary scripts from the cgi-bin directory. If CGI functionality is required, restrict it to only necessary, vetted scripts and disable direct interpreter access.

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

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
Authentication
None
Confidentiality
Complete
Integrity
Complete
Availability
Complete

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

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. Locate the cgi-bin directory
    Search the web server's document root and configuration for directories named 'cgi-bin' or 'cgi'. Common locations include /var/www/cgi-bin/, /usr/local/apache/cgi-bin/, or C:\Inetpub\cgi-bin\. Check httpd.conf or equivalent web server config for the ScriptAlias directive that defines the CGI directory.
    Affected if A cgi-bin directory exists and is mapped as a CGI script alias on the web server.
  2. List contents of cgi-bin for interpreter files
    Examine all files in the identified cgi-bin directory. Look for files with extensions such as .pl (Perl), .sh (shell), .csh (C shell), .py (Python), or any executable scripts without extensions that may be shell scripts. Also note any files named 'perl', 'sh', 'csh', 'bash', or similar interpreter names.
    Affected if Shell interpreter files (perl*, sh, csh, bash) or scripts with interpreter directives (#!/bin/sh, #!/usr/bin/perl) are present in cgi-bin.
  3. Test HTTP access to interpreter scripts
    Attempt to access potential interpreter scripts via HTTP using a web browser or curl. For example: GET /cgi-bin/perl HTTP/1.1 or GET /cgi-bin/someScript.pl HTTP/1.1. If the server responds with script output or an error message indicating the interpreter executed, direct HTTP invocation is possible.
    Affected if The web server executes the script and returns output when the file is requested via HTTP, rather than prompting for download or returning a 403/404.
  4. Verify CGI is enabled in web server configuration
    Check the web server configuration file (httpd.conf, nginx.conf, etc.) for the presence of 'ScriptAlias' directives, 'AddHandler cgi-script', or 'Options +ExecCGI' settings that enable CGI execution. For IIS, check for CGI or ISAPI extensions being enabled.
    Affected if CGI execution is explicitly enabled via configuration, allowing the web server to treat files in cgi-bin as executable scripts.
  5. Check file permissions on cgi-bin contents
    Review file permissions on contents of the cgi-bin directory. Determine if the web server process user has execute permissions on the interpreter files and scripts found. On Unix/Linux, use 'ls -la' in the cgi-bin directory. On Windows, check NTFS permissions.
    Affected if The web server user (e.g., www-data, apache, IUSR) has execute permissions on shell interpreter files in cgi-bin.

If a cgi-bin directory exists with accessible shell interpreter files (perl, sh, csh, or similar) and CGI is enabled, the server is affected by allowing remote command execution via HTTP requests to these interpreters.

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.

From vendor data
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Remove all shell interpreters and unnecessary scripts from the cgi-bin directory. If CGI functionality is required, restrict it to only necessary, vetted scripts and disable direct interpreter access.

Have this fixed Scoped from the published advisory
  • Consultation2.0 h
  • Implementation2.0 h
  • Testing2.0 h
  • Review / QA1.0 h
7.0 hours of engineering $1,240
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Scan for this in your stack

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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-1999-0509 in production — separate from our analysis above.

No notes yet

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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
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