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ContaoApplication

CVE-2018-5478

MEDIUM · 6.1 CVSS v3.1 Published 2023-09-21
Fix available
A fix is available. Upgrade to 3.5.32 or later.
See remediation →
68/100
Remediation priority · Elevated
Remotely reachable No privileges

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
Contao 3.x before 3.5.32 allows XSS via the unsubscribe module in the frontend newsletter extension.

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

Contao 3.x before version 3.5.32 contains a cross-site scripting (XSS) vulnerability in the unsubscribe module of the frontend newsletter extension. An attacker could inject malicious scripts through unsanitized input in the unsubscribe functionality, potentially stealing session cookies or performing actions on behalf of authenticated users.

MitigationUpgrade Contao to version 3.5.32 or later to obtain the patched version of the newsletter extension. If immediate upgrade is not possible, implement input sanitization on all user-supplied parameters in the unsubscribe module.

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
ContaoApplication
Affected:>= 3.0.0, < 3.5.32

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
Required
Scope
Changed
Confidentiality
Low
Integrity
Low
Availability
None

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/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. Identify Contao installation and version
    Locate the Contao installation directory and check the version file or system information panel. Typical locations include a version.php, composer.json, or the Contao Manager. Look for a file containing the version number or access the system information in the Contao back end.
    Affected if The installed Contao version is 3.x and is lower than 3.5.32 (for example, 3.5.0 through 3.5.31 are affected).
  2. Verify the newsletter extension is present
    Check whether the Contao newsletter extension (tl_newsletter) is installed and enabled. This can be done by examining the installed extensions in the Contao back end under Extensions, or by looking for the newsletter-related database tables or files in the system.
    Affected if The newsletter extension is installed and active in the Contao installation.
  3. Confirm the unsubscribe module is in use
    Determine if the frontend newsletter unsubscribe functionality is accessible or active on the website. This may include checking for unsubscribe forms on the front end, reviewing the page layout modules, or verifying that newsletter subscription functionality exists.
    Affected if The unsubscribe module is enabled and accessible on the front end, allowing user input for unsubscribing from newsletters.
  4. Review unsubscribe form for sanitization
    If you have access to the source code, inspect the unsubscribe form handling in the newsletter extension files. Look for how user-supplied input (such as email addresses or subscription tokens) is processed and whether proper output encoding or input sanitization is applied before rendering.
    Affected if The unsubscribe functionality does not properly sanitize user input before displaying it, allowing script injection through form fields.

A Contao 3.x installation with version lower than 3.5.32 that has the newsletter extension enabled with an accessible unsubscribe module is affected by this XSS vulnerability.

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 3.5.32 or later
Fixed in 3.5.32
Interim mitigation

Upgrade Contao to version 3.5.32 or later to obtain the patched version of the newsletter extension. If immediate upgrade is not possible, implement input sanitization on all user-supplied parameters in the unsubscribe module.

Recommended fix High confidence

Contao 3.5.32 or later (within the 3.x branch)

  1. 1. Backup your Contao installation and database before proceeding
  2. 2. Download Contao version 3.5.32 or later from the official Contao download page (contao.org)
  3. 3. Replace the existing Contao core files with the new version files, preserving your local configuration
  4. 4. Run the Contao Install Tool to apply any necessary database updates
  5. 5. Clear the application cache after the upgrade
  6. 6. Test the newsletter unsubscribe functionality to verify the XSS vulnerability is resolved
Caveat Patch releases in the 3.5.x series typically contain only bug and security fixes with minimal risk of breaking changes

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

Fix this in Contao 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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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-2018-5478 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