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HTTP ServerWeb server / proxy · Apache

CVE-2025-66200

MEDIUM · 5.4 CVSS v3.1 Published 2025-12-05
Fix available
A fix is available. Upgrade to 2.4.66 or later.
See remediation →
60/100
Remediation priority · Elevated
Remotely reachable 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_userdir+suexec bypass via AllowOverride FileInfo vulnerability in Apache HTTP Server. Users with access to use the RequestHeader directive in htaccess can cause some CGI scripts to run under an unexpected userid. This issue affects Apache HTTP Server: from 2.4.7 through 2.4.65. Users are recommended to upgrade to version 2.4.66, which fixes the issue.

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

This is an authorization bypass vulnerability in Apache HTTP Server where the combination of mod_userdir and suexec can be bypassed through AllowOverride FileInfo settings. Attackers with the ability to use the RequestHeader directive in .htaccess files can cause CGI scripts to execute under an unexpected user ID, bypassing the intended user isolation provided by mod_userdir+suexec.

MitigationUpgrade Apache HTTP Server to version 2.4.66 or later. Additionally, restrict AllowOverride settings to limit which directives users can use in .htaccess files, avoiding FileInfo unless absolutely necessary.

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:>= 2.4.7, < 2.4.66

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
Low
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
Low
Availability
Low

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:L

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. Check installed Apache version
    Run 'httpd -v' or 'apache2 -v' to retrieve the server version number
    Affected if Version is >= 2.4.7 and < 2.4.66
  2. Verify mod_userdir is enabled
    Run 'httpd -M' or 'apache2ctl -M' and look for 'userdir_module' in the loaded modules list
    Affected if mod_userdir is loaded and active
  3. Confirm suexec is being used
    Check for 'SuexecUserGroup' directives in the Apache configuration files, or verify the suexec binary exists at its expected path
    Affected if suexec is configured for CGI script execution
  4. Inspect AllowOverride settings
    Search configuration files for 'AllowOverride' directives, particularly within <Directory> blocks that apply to user directories (e.g., /home/*/public_html or UserDir paths)
    Affected if AllowOverride includes 'FileInfo' or is set to 'All' for user-accessible directories
  5. Check for .htaccess files with RequestHeader capability
    Examine .htaccess files in user directories (typically under ~/public_html) to see if RequestHeader directive is permitted or actively used
    Affected if Users can use RequestHeader in their .htaccess files due to AllowOverride FileInfo setting

Your environment is affected if you run Apache 2.4.7-2.4.65 with mod_userdir enabled, suexec in use, and AllowOverride FileInfo (or All) configured for user directories, allowing .htaccess files to contain RequestHeader 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 2.4.66 or later
Fixed in 2.4.66
Interim mitigation

Upgrade Apache HTTP Server to version 2.4.66 or later. Additionally, restrict AllowOverride settings to limit which directives users can use in .htaccess files, avoiding FileInfo unless absolutely necessary.

Recommended fix High confidence

2.4.66

  1. 1. Back up your current Apache HTTP Server configuration and website files.
  2. 2. Stop the Apache HTTP Server service (e.g., systemctl stop httpd or apache2ctl stop).
  3. 3. Obtain Apache HTTP Server version 2.4.66 from the official Apache download page (httpd.apache.org) or your distribution's package repository.
  4. 4. Install version 2.4.66 using your system's package manager or by compiling from source.
  5. 5. Restore your Apache configuration files from the backup if needed.
  6. 6. Start the Apache HTTP Server service (e.g., systemctl start httpd or apache2ctl start).
  7. 7. Verify the server is running the fixed version using 'httpd -v' or 'apache2ctl -V'.
Caveat Minor patch release; backward compatible with 2.4.x configurations

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

Fix this in HTTP Server Scoped from the published advisory
  • Consultation2.0 h
  • Implementation3.0 h
  • Testing2.0 h
  • Review / QA1.0 h
8.0 hours of engineering $1,420
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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-2025-66200 in production — separate from our analysis above.

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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