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Actively exploited in the wild. This CVE is on the CISA Known Exploited Vulnerabilities list — treat remediation as urgent. Federal remediation due by 6 Feb 2024.
LaravelFramework / library

CVE-2018-15133

HIGH · 8.1 CVSS v3.1 Published 2018-08-09
Fix available
A fix is available. Upgrade to after 5.6.29 or later.
See remediation →
100/100
Remediation priority · Urgent
In the wild High EPSS Public exploit 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
In Laravel Framework through 5.5.40 and 5.6.x through 5.6.29, remote code execution might occur as a result of an unserialize call on a potentially untrusted X-XSRF-TOKEN value. This involves the decrypt method in Illuminate/Encryption/Encrypter.php and PendingBroadcast in gadgetchains/Laravel/RCE/3/chain.php in phpggc. The attacker must know the application key, which normally would never occur, but could happen if the attacker previously had privileged access or successfully accomplished a previous attack.

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

Laravel Framework through 5.5.40 and 5.6.x through 5.6.29 contains a PHP unserialize vulnerability in the decrypt method of Illuminate/Encryption/Encrypter.php. When the X-XSRF-TOKEN header value is decrypted, it uses unserialize() on potentially untrusted data, which can trigger a gadget chain (specifically the Laravel/RCE/3 chain in phpggc) leading to remote code execution. The attack requires the attacker to know the application key.

MitigationUpdate Laravel to version 5.5.41, 5.6.30, or later where the vulnerable unserialize call is replaced with safe deserialization. Additionally, rotate the application key if there is any suspicion it has been compromised, as the exploit requires knowledge of this key.

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
LaravelFramework / library
Affected:<= 5.5.40>= 5.6.0, <= 5.6.29

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
High
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:H/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. Verify Laravel version
    Check the version of your Laravel installation by examining the composer.json file or running `php artisan --version` in your project directory
    Affected if The installed version is 5.5.x at 5.5.40 or lower, OR 5.6.x at 5.6.29 or lower
  2. Confirm application key is configured
    Locate the APP_KEY value in your .env file or config/app.php configuration file
    Affected if An APP_KEY is currently set and exists in your environment configuration (the exploit requires knowledge of this key)
  3. Check if CSRF token handling is active
    Review your routes and middleware configuration to determine if the VerifyCsrfToken middleware is enabled and handling X-XSRF-TOKEN headers
    Affected if The VerifyCsrfToken middleware is active and the application processes X-XSRF-TOKEN headers from incoming requests

You are affected if your Laravel version falls within 5.5.40 or lower / 5.6.0-5.6.29 AND you have an application key configured AND CSRF token processing is enabled.

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 5.6.29
Interim mitigation

Update Laravel to version 5.5.41, 5.6.30, or later where the vulnerable unserialize call is replaced with safe deserialization. Additionally, rotate the application key if there is any suspicion it has been compromised, as the exploit requires knowledge of this key.

Recommended fix High confidence

Laravel 5.5.41+ or 5.6.30+ (preferably latest 5.6.x or upgrade to Laravel 7/8)

  1. 1. Check your current Laravel version by running `php artisan --version` in your application root
  2. 2. For Laravel 5.5.x users: Upgrade to Laravel 5.5.41 or later by running `composer update laravel/framework`
  3. 3. For Laravel 5.6.x users: Upgrade to Laravel 5.6.30 or later by running `composer update laravel/framework`
  4. 4. After upgrading, clear the application cache with `php artisan cache:clear`
  5. 5. Regenerate the application key if needed with `php artisan key:generate`
  6. 6. Ensure your APP_KEY in .env uses a secure, random 32-character key
Caveat Minor point releases typically have no breaking changes; upgrading within same minor version (e.g., 5.6.x to 5.6.30) is low risk

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

Fix this in Laravel Exploited in the wild — priority engagement
  • Consultation2.0 h
  • Implementation3.0 h
  • Testing3.0 h
  • Review / QA2.0 h
10.0 hours of engineering $1,750
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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-2018-15133 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