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Virtual Computing LabApplication · Apache

CVE-2018-11773

CRITICAL · 9.8 CVSS v3.0 Published 2019-07-29
Fix available
A fix is available. Upgrade to after 2.5 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
Apache VCL versions 2.1 through 2.5 do not properly validate form input when processing a submitted block allocation. The form data is then used as an argument to the php built in function strtotime. This allows for an attack against the underlying implementation of that function. The implementation of strtotime at the time the issue was discovered appeared to be resistant to a malicious attack. However, all VCL systems running versions earlier than 2.5.1 should be upgraded or patched. This vulnerability was found and reported to the Apache VCL project by ADLab of Venustech.

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

Apache VCL versions 2.1-2.5 fail to validate form input in block allocation processing, directly passing user-submitted data to PHP's strtotime() function without sanitization. This allows injection of malicious input against the date parsing implementation, potentially leading to code execution or denial of service.

MitigationUpgrade to Apache VCL 2.5.1 or later to obtain the patched version, or implement server-side input validation to sanitize all form data before use with strtotime().

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
Virtual Computing LabApplication
Affected:>= 2.1, <= 2.5

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:3.0/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. Identify installed Apache VCL version
    Locate the VCL version file or check the admin interface for the current version number. Common locations include the footer of web pages, a version info file in the installation directory, or the database.
    Affected if The installed version is 2.1, 2.2, 2.3, 2.4, or 2.5 (any version from 2.1 through 2.5 inclusive)
  2. Confirm block allocation feature is accessible
    Navigate to the block allocation section of the VCL management interface or check if the /blockalloc or similar allocation endpoint exists and is accessible to users.
    Affected if Block allocation functionality is enabled and accessible to users in the environment
  3. Verify the vulnerable code path exists
    Examine the PHP source code in the block allocation handling files, specifically looking for strtotime() calls that receive user-submitted form data without prior validation. Search for strtotime() in files related to reservation or allocation processing.
    Affected if The strtotime() function is called with direct user input from forms without sanitization in the allocation code
  4. Test if user input reaches strtotime unsanitized
    Submit a specially crafted date string (such as those that cause excessive parsing time or unexpected behavior in PHP's strtotime) through block allocation forms and observe if the application processes it without validation errors.
    Affected if The application accepts and processes arbitrary strings in date fields without rejecting malformed input

The environment is affected if Apache VCL version 2.1 through 2.5 is installed and the block allocation feature is accessible, with the vulnerable strtotime() call handling user input directly.

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 2.5
Interim mitigation

Upgrade to Apache VCL 2.5.1 or later to obtain the patched version, or implement server-side input validation to sanitize all form data before use with strtotime().

Recommended fix High confidence

2.5.1

  1. Back up the existing Apache VCL database and web application files
  2. Download Apache VCL version 2.5.1 from the official Apache download repository (https://vcl.apache.org/)
  3. Consult the Apache VCL upgrade documentation for version 2.5.1
  4. Stop the Apache VCL web service
  5. Install the version 2.5.1 files, preserving the existing database configuration
  6. Start the Apache VCL web service
  7. Verify that the block allocation form now properly validates input before passing to strtotime()

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

Fix this in Virtual Computing Lab Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing6.0 h
  • Review / QA2.0 h
20.0 hours of engineering $3,500
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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-2018-11773 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