Package Instance

Craft CMS vulnerable to potential authenticated Remote Code Execution via Twig SSTI
For this to work, users must have administrator access to the Craft Control Panel, and [allowAdminChanges](https://craftcms.com/docs/5.x/reference/config/general.html#allowadminchanges) must be enabled for this to work, which is against Craft CMS' recommendations for any non-dev environment.

https://craftcms.com/knowledge-base/securing-craft#set-allowAdminChanges-to-false-in-production

Alternatively, a non-administrator account with allowAdminChanges disabled can be used, provided access to the System Messages utility is available.

It is possible to craft a malicious payload using the Twig `map` filter in text fields that accept Twig input under Settings in the Craft control panel or using the System Messages utility, which could lead to a RCE.

Users should update to the patched versions (5.8.21 and 4.16.17) to mitigate the issue.

References:

https://github.com/craftcms/cms/commit/d82680f4a05f9576883bb83c3f6243d33ca73ebe

https://github.com/craftcms/cms/blob/5.x/CHANGELOG.md#5821---2025-12-04

Craft CMS Vulnerable to Authenticated RCE via "craft.app.fs.write()" in Twig Templates
An authenticated administrator can achieve Remote Code Execution (RCE) by injecting a Server-Side Template Injection (SSTI) payload into Twig template fields (e.g., Email Templates). By calling the `craft.app.fs.write()` method, an attacker can write a malicious PHP script to a web-accessible directory and subsequently access it via the browser to execute arbitrary system commands.

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Craft CMS Vulnerable to SSRF in GraphQL Asset Mutation via Alternative IP Notation
The `saveAsset` GraphQL mutation uses `filter_var(..., FILTER_VALIDATE_IP)` to block a specific list of IP addresses. However, alternative IP notations (hexadecimal, mixed) are not recognized by this function, allowing attackers to bypass the blocklist and access cloud metadata services.

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Craft CMS vulnerable to potential information disclosure via unchecked asset relocation
Authenticated users on a Craft installation could potentially expose sensitive assets via their user profile photo via maliciously crafted requests.

Users should update to the patched versions (5.8.21 and 4.16.17) to mitigate the issue.

 Resources:

https://github.com/craftcms/cms/commit/4bcb0db554e273b66ce3b75263a13414c2368fc9

https://github.com/craftcms/cms/commit/4bcb0db554e273b66ce3b75263a13414c2368fc9

Craft CMS vulnerable to Remote Code Execution via validatePath bypass
Bypassing the validatePath function can lead to potential Remote Code Execution
(Post-authentication, ALLOW_ADMIN_CHANGES=true)

Craft CMS has a potential information disclosure vulnerability in preview tokens
Craft CMS has a CSRF issue in the preview token endpoint at `/actions/preview/create-token`.  The endpoint accepts an attacker-supplied `previewToken`.

Because the action does not require POST and does not enforce a CSRF token, an attacker can force a logged-in victim editor to mint a preview token chosen by the attacker.

That token can then be used by the attacker (without authentication) to access previewed/unpublished content tied to the victim’s authorized preview scope.

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Craft CMS vulnerable to potential authenticated Remote Code Execution via malicious attached Behavior
This was reported as a vulnerability in Yii framework on August 7th (https://github.com/yiisoft/yii2/security/advisories/GHSA-gcmh-9pjj-7fp4). The Yii framework team denies responsibility for this (placing the onus on application developers) and hence has not (and seemingly will not) provide a fix at the framework level. Hence, I am reporting this to Craft as I found it to affect the latest (`5.6.0`) version of Craft CMS.

Leveraging a legitimate but maliciously crafted Yii `Behavior` class, it’s possible to trigger Remote Code Execution (RCE) via Reflection when the tainted `Behavior` is attached to a Yii `Component`, and an event is also fired on the tainted `Component`.

Craft CMS Vulnerable to Stored XSS in Number Prefix & Suffix Fields
A stored XSS vulnerability exists in the Number field type settings. The Prefix and Suffix fields are rendered using the `|md|raw` Twig filter without proper escaping, allowing script execution when the Number field is displayed on users' profiles.

Craft CMS: GraphQL Asset Mutation Privilege Escalation
Type: Privilege Escalation (CWE-269)
Affected: Craft CMS 5.x (likely affects 4.x and 3.x as well)
Location: `src/gql/resolvers/mutations/Asset.php lines 57-107`

Craft CMS has Permission Bypass and IDOR in Duplicate Entry Action
The "Duplicate" entry action does not properly verify if the user has permission to perform this action on the specific target elements.
Even with only "View Entries" permission (where the "Duplicate" action is restricted in the UI), a user can bypass this restriction by sending a direct request.

Furthermore, this vulnerability allows duplicating **other users' entries** by specifying their Entry IDs. Since Entry IDs are incremental, an attacker can trivially brute-force these IDs to duplicate and access restricted content across the system.

Craft CMS has Twig Function Blocklist Bypass
Craft CMS implements a blocklist to prevent potentially dangerous PHP functions from being called via Twig non-Closure arrow functions.

In order to be able to successfully execute this attack, you need to either have `allowAdminChanges` enabled on production, or a compromised admin account, or an account with access to the System Messages utility.

Several PHP functions are not included in the blocklist, which could allow malicious actors with the required permissions to execute various types of payloads, including RCEs, arbitrary file reads, SSRFs, and SSTIs.

Twig has already deprecated this behavior, and it will eventually be removed from Twig altogether.

https://github.com/twigphp/Twig/blob/946ddeafa3c9f4ce279d1f34051af041db0e16f2/src/Extension/CoreExtension.php#L2096

This has been resolved in Craft 4.17.0 and 5.9.0, which removes the blocklist and disables all non-Clousure arrow functions in Twig globally via the `enableTwigSandbox` config setting. That setting is enabled by default on all new Craft projects. Existing Craft projects will need to enable the config setting to take advantage of it.

Existing projects should update to the patched versions of 5.9.0 and 4.17.0 to mitigate the issue and enable the config setting.

Craft CMS has potential authenticated Remote Code Execution via Twig SSTI
For this to work, the attacker must have administrator access to the Craft Control Panel, and [allowAdminChanges](https://craftcms.com/docs/5.x/reference/config/general.html#allowadminchanges) must be enabled, which is against Craft CMS' recommendations for any non-dev environment.

https://craftcms.com/knowledge-base/securing-craft#set-allowAdminChanges-to-false-in-production

Alternatively, they can have a non-administrator account with `allowAdminChanges` disabled, but they must have access to the System Messages utility.

It is possible to craft a malicious payload using the Twig `map` filter in text fields that accept Twig input under Settings in the Craft control panel or using the System Messages utility, which could lead to a RCE.

Users should update to the patched versions (5.8.22 and 4.16.18) to mitigate the issue.

References:

https://github.com/craftcms/cms/pull/18208

Craft CMS Vulnerable to potential authenticated Remote Code Execution via malicious attached Behavior
A Remote Code Execution (RCE) vulnerability exists in Craft CMS where the `assembleLayoutFromPost()` function in `src/services/Fields.php` fails to sanitize user-supplied configuration data before passing it to `Craft::createObject()`. This allows authenticated administrators to inject malicious Yii2 behavior configurations that execute arbitrary system commands on the server. This vulnerability represents an **unpatched variant** of the behavior injection vulnerability addressed in GHSA-255j-qw47-wjh5, affecting different endpoints through a separate code path.

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