dbcve.org
HTTP ServerWeb server / proxy · Apache

CVE-2003-0020

MEDIUM · 5.0 CVSS v2.0 Published 2003-03-18
Fix available
A fix is available. Upgrade to 1.3.31 / 2.0.49 or later.
See remediation →
59/100
Remediation priority · Elevated
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
Apache does not filter terminal escape sequences from its error logs, which could make it easier for attackers to insert those sequences into terminal emulators containing vulnerabilities related to escape sequences.

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 · moderate confidence

Apache HTTP Server does not filter or sanitize terminal escape sequences from error log output. When attackers craft HTTP requests that generate errors (such as requests with malformed headers or invalid URLs), any terminal escape sequences embedded in those requests can be written directly to the error log. Administrators viewing these logs with vulnerable terminal emulators may then be exposed to commands executed via escape sequence injection.

MitigationUpgrade to a patched version of Apache that filters terminal escape sequences, or implement a log filtering layer that strips escape sequences before logs are displayed or stored.

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
HTTP ServerWeb server / proxy
Affected:>= 1.3.0, < 1.3.31>= 2.0.0, < 2.0.49

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
None
Integrity
Partial
Availability
None

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

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. Determine installed Apache version
    Run 'apachectl -v' or 'httpd -v' to see the server version. On some systems, check '/usr/sbin/apachectl -v' or look for version in the binary.
    Affected if Version is 1.3.x below 1.3.31, or 2.0.x below 2.0.49
  2. Verify error logging is active
    Check the Apache configuration file (httpd.conf or apache2.conf) for the ErrorLog directive. Look for 'ErrorLog /path/to/error_log' or similar. Also verify LogLevel is set to a level that generates logs (e.g., 'LogLevel warn').
    Affected if Error logging is enabled and logs are being written; the flaw requires error logs to be generated for malicious escape sequences to be injected
  3. Confirm error log location is accessible
    Check if the configured error log file exists and is writable by the Apache process. Verify the path from the ErrorLog directive in the configuration.
    Affected if Error logs are being written to a file that administrators view with terminal emulators; the attack requires an admin to view contaminated logs in a vulnerable terminal

Your environment is affected if Apache 1.3.0-1.3.30 or 2.0.0-2.0.48 is installed with error logging enabled, and administrators view error logs in terminal emulators that interpret escape sequences.

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
Upgrade available Upgrade to 1.3.31 / 2.0.49 or later
Fixed in 1.3.312.0.49
Interim mitigation

Upgrade to a patched version of Apache that filters terminal escape sequences, or implement a log filtering layer that strips escape sequences before logs are displayed or stored.

Fix this in HTTP Server Scoped from the published advisory
  • Consultation2.0 h
  • Implementation2.0 h
  • Testing1.0 h
  • Review / QA1.0 h
6.0 hours of engineering $1,090
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,744.

Scan for this in your stack

Free · runs locally
dbcve dependency scanner

Check whether your project pulls in CVE-2003-0020 — 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-2003-0020 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