cms: Improper Neutralization of Special Elements Used in a Template Engine
CVE-2026-28784 is a high-severity improper neutralization of special elements used in a template engine vulnerability in cms from Craft CMS, with a CVSS 3.1 base score of 7.2 out of 10. It can be exploited remotely over the network by an attacker with administrator privileges, without any action from a user. Affected cms versions: >= 5.0.0-RC1, < 5.9.0-beta.1; >= 4.0.0-RC1, < 4.17.0-beta.1. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 0.59% chance of exploitation within 30 days, which is low compared with other CVEs.
High severity with no evidence of exploitation so far.
What to do
- Update Craft CMS to 4.17.0 or 5.9.0, whichever matches your release line, or a later version.
- Read the advisory on github.com for workarounds and exact fixed builds.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Craft CMS | cms | >= 5.0.0-RC1, < 5.9.0-beta.1; >= 4.0.0-RC1, < 4.17.0-beta.1 | Not stated |
| Craft CMS | Craft CMS | after 4.0.0 up to, but not including, 4.17.0; after 5.0.0 up to, but not including, 5.9.0; 4.0.0; 5.0.0 | 4.17.0, 5.9.0 |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- HighAdministrator-level access is required first.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- HighData or code can be modified at will.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 4.0 | 8.6 | High | CNA (github.com) |
| CVSS 3.1 | 7.2 | High | NVD |
Official description
Craft is a content management system (CMS). Prior to 5.8.22 and 4.16.18, 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. For this to work, you must have administrator access to the Craft Control Panel, and allowAdminChanges must be enabled for this to work, which is against our recommendations for any non-dev environment. Alternatively, you can have a non-administrator account with allowAdminChanges disabled, but you have access to the System Messages utility. Users should update to the patched versions (5.8.22 and 4.16.18) to mitigate the issue.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Improper Neutralization of Special Elements Used in a Template Engine
The product uses a template engine to insert or process externally-influenced input, but it does not neutralize or incorrectly neutralizes special elements or syntax that can be interpreted as template expressions or other code directives when processed by the engine.
How developers prevent this class of flaw
- Choose a template engine that offers a sandbox or restricted mode, or at least limits the power of any available expressions, function calls, or commands.
- Use the template engine's sandbox or restricted mode, if available.
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
- github.com/craftcms/cms/pull/18208Issue Tracking
Other references
Other vulnerabilities in cms
- 9.8 Critical severity
- 8.8 High severity
- 7.5 High severity
- 9.8 Critical severity
- 8.2 High severity
- 8.8 High severity
Recent Improper Neutralization of Special Elements Used in a Template Engine vulnerabilities
- 9.1 Critical severity
- 7.2 High severity
- 7.7 High severity
- 8.8 High severity
- 8.8 High severity
- 9.9 Critical severity
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