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GoaheadApplication · Embedthis

CVE-2021-42342

CRITICAL · 9.8 CVSS v3.1 Published 2021-10-14
Fix available
A fix is available. Upgrade to 5.1.5 or later.
See remediation →
100/100
Remediation priority · Urgent
High EPSS 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
An issue was discovered in GoAhead 4.x and 5.x before 5.1.5. In the file upload filter, user form variables can be passed to CGI scripts without being prefixed with the CGI prefix. This permits tunneling untrusted environment variables into vulnerable CGI scripts.

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

GoAhead web server versions 4.x and 5.x before 5.1.5 have a vulnerability in the file upload filter where user form variables can be passed to CGI scripts without the required CGI prefix. This allows attackers to inject untrusted environment variables directly into CGI scripts, potentially leading to command injection or unauthorized access.

MitigationUpgrade GoAhead to version 5.1.5 or later. As a temporary workaround, disable CGI script execution or implement input validation on the file upload handler to enforce proper CGI variable prefixing before the fix can be applied.

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
GoaheadApplication
Affected:>= 4.0.0, <= 4.1.3>= 5.0.0, < 5.1.5

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:3.1/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. Identify GoAhead installation
    Locate the GoAhead web server binary or service. Common locations: /usr/sbin/goahead, /opt/goahead/bin/goahead, or check system services. On Windows, look for goahead.exe in installation directories.
    Affected if GoAhead is not installed or not found - not affected.
  2. Determine installed version
    Run 'goahead -v' or 'goahead --version' to display the version. Alternatively, check the binary file metadata or package manager listing (dpkg -l goahead, rpm -qi goahead).
    Affected if Version is 4.0.0 through 4.1.3, or 5.0.0 through 5.1.4 - potentially affected.
  3. Check if CGI is enabled
    Examine the GoAhead configuration file (goahead.conf or app.conf) for 'CgiEnabled' directive or CGI route handler configuration. Look for entries like 'route uri=/cgi/*' with handler=cgi.
    Affected if CGI execution is enabled in configuration - vulnerable condition present.
  4. Check file upload handler configuration
    Inspect the GoAhead configuration for file upload form handling. Look for 'UploadDir' directive, form variable handling, or multipart form processing configuration related to CGI variable passing.
    Affected if File upload handler is configured and passes variables to CGI scripts - vulnerable condition present.
  5. Verify runtime process
    Check if GoAhead is actively running as a service or daemon. Use 'ps aux | grep goahead' on Linux or check Services on Windows.
    Affected if GoAhead server is not running - no active exposure.

Affected if running GoAhead version 4.0.0-4.1.3 or 5.0.0-5.1.4 with CGI enabled and file upload handler configured to pass variables to CGI scripts.

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 5.1.5 or later
Fixed in 5.1.5
Interim mitigation

Upgrade GoAhead to version 5.1.5 or later. As a temporary workaround, disable CGI script execution or implement input validation on the file upload handler to enforce proper CGI variable prefixing before the fix can be applied.

Recommended fix Moderate confidence

5.1.5 or later (or 4.1.4+ if a 4.x branch fix was released)

  1. 1. Identify all GoAhead server instances running affected versions (4.0.0-4.1.3 or 5.0.0-5.1.4)
  2. 2. Back up current configuration files and any custom scripts
  3. 3. Download GoAhead version 5.1.5 or later from the official GitHub repository (https://github.com/embedthis/goahead)
  4. 4. Stop the GoAhead service on all affected servers
  5. 5. Replace the existing GoAhead binaries with the updated version
  6. 6. Restore backed-up configuration files
  7. 7. Verify that CGI scripts are still functioning correctly after the upgrade
  8. 8. Test the file upload functionality to confirm the vulnerability is remediated
Caveat The upgrade may include other changes; review release notes for behavioral changes or deprecated features

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

Fix this in Goahead Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing3.0 h
  • Review / QA2.0 h
11.0 hours of engineering $1,930
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $3,088.

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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-2021-42342 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
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data