CVE-2026-28783: Craftcms/cms Craft CMS Has Twig Function Vulnerability

MODERATE
Advisory Identifier: GHSA-5fvc-7894-ghp4
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CWE-94 CWE-1336 CWE-184
Published
Advisory Summary

CVE-2026-28783 is a MODERATE craft cms has twig function vulnerability (CWE-94: Improper Control of Generation of Code ('Code Injection')) affecting Craftcms/cms libraries in the Packagist ecosystem. The issue involves craft cms has twig function blocklist bypass. Remediation is available by upgrading affected packages to version 5.9.0-beta.1, 4.17.0-beta.1.

CVE-2026-28783 at a Glance

CVE Identifier CVE-2026-28783
GHSA Identifier GHSA-5fvc-7894-ghp4
Severity MODERATE
CVSS v3.1 Base Score N/A
CWE Classification CWE-94: Improper Control of Generation of Code ('Code Injection')
Affected Product Craftcms/cms
Package Ecosystem Packagist
Published Date
Last Updated

How to Fix CVE-2026-28783

To remediate this vulnerability, upgrade all affected Craftcms/cms dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

craftcms/cms fixed: 5.9.0-beta.1 
Upgrade craftcms/cms to 5.9.0-beta.1
craftcms/cms fixed: 4.17.0-beta.1 
Upgrade craftcms/cms to 4.17.0-beta.1
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

inspect dependencies for craftcms/cms

How to Check if You Are Affected

To determine whether your application is affected by CVE-2026-28783, inspect your project dependencies for Craftcms/cms:

inspect dependencies for craftcms/cms

Analyze the terminal output to locate any version of Craftcms/cms in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 5.9.0-beta.1), your application is affected.

Note: Verify declared build manifests and deployed runtime container environments.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-94: Improper Control of Generation of Code ('Code Injection'), where the product constructs all or part of a code segment using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the syntax or behavior of the intended code segment. In Craftcms/cms, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

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

CVE-2026-28783 Affected Craftcms/cms Versions

2 component(s)
Fixed Versions:
5.9.0-beta.14.17.0-beta.1
Product / Package Ecosystem Affected Versions Fixed Version
craftcms/cms
 Packagist
≥ 5.0.0-RC1
< 5.9.0-beta.1
5.9.0-beta.1
craftcms/cms
 Packagist
≥ 4.0.0-RC1
< 4.17.0-beta.1
4.17.0-beta.1

References

GitHub Advisory / Wiki ADVISORY
https://github.com/craftcms/cms/security/advisories/GHSA-5fvc-7894-ghp4
NVD — CVE-2026-28783 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-28783
Craftcms/cms Source Repository REPOSITORY
https://github.com/craftcms/cms/pull/18208
Craftcms/cms Source Repository REPOSITORY
https://github.com/craftcms/cms
Craftcms/cms Source Repository REPOSITORY
https://github.com/twigphp/Twig/blob/946ddeafa3c9f4ce279d1f34051af041db0e16f2/src/Extension/CoreExtension.php#L2096

Frequently Asked Questions

What is CVE-2026-28783?
CVE-2026-28783 is a security vulnerability in Craftcms/cms involving Craft CMS has Twig Function Blocklist Bypass under CWE-94: Improper Control of Generation of Code ('Code Injection').
Which Craftcms/cms versions are affected?
Affected versions include releases prior to 5.9.0-beta.1, 4.17.0-beta.1 across affected packages: craftcms/cms.
What version fixes CVE-2026-28783?
Upgrading to 5.9.0-beta.1, 4.17.0-beta.1 (or the latest patched release for your respective branch) resolves the vulnerability.
Is craftcms/cms affected?
Yes, craftcms/cms is affected in releases prior to 5.9.0-beta.1, 4.17.0-beta.1. Upgrade your dependency to 5.9.0-beta.1, 4.17.0-beta.1 or later.
What CWE is associated with CVE-2026-28783?
CVE-2026-28783 is classified under CWE-94: Improper Control of Generation of Code ('Code Injection') (The product constructs all or part of a code segment using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the syntax or behavior of the intended code segment.).
How can I check Packagist dependencies for CVE-2026-28783?
Run the dependency tree command: 'inspect dependencies for craftcms/cms'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-5fvc-7894-ghp4",
  "modified" : "2026-03-04T18:39:13Z",
  "published" : "2026-03-03T21:01:27Z",
  "aliases" : [ "CVE-2026-28783" ],
  "summary" : "Craft CMS has Twig Function Blocklist Bypass",
  "details" : "Craft CMS implements a blocklist to prevent potentially dangerous PHP functions from being called via Twig non-Closure arrow functions.\n\nIn 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.\n\nSeveral 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.\n\nTwig has already deprecated this behavior, and it will eventually be removed from Twig altogether.\n\nhttps://github.com/twigphp/Twig/blob/946ddeafa3c9f4ce279d1f34051af041db0e16f2/src/Extension/CoreExtension.php#L2096\n\nThis 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.\n\nExisting projects should update to the patched versions of 5.9.0 and 4.17.0 to mitigate the issue and enable the config setting.\n\n## Resources\n\nhttps://github.com/craftcms/cms/pull/18208",
  "severity" : [ {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:U"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Packagist",
      "name" : "craftcms/cms"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "5.0.0-RC1"
      }, {
        "fixed" : "5.9.0-beta.1"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "Packagist",
      "name" : "craftcms/cms"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "4.0.0-RC1"
      }, {
        "fixed" : "4.17.0-beta.1"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/craftcms/cms/security/advisories/GHSA-5fvc-7894-ghp4"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-28783"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/craftcms/cms/pull/18208"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/craftcms/cms"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/twigphp/Twig/blob/946ddeafa3c9f4ce279d1f34051af041db0e16f2/src/Extension/CoreExtension.php#L2096"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-1336", "CWE-184", "CWE-94" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-03-03T21:01:27Z",
    "nvd_published_at" : "2026-03-04T17:16:21Z"
  }
}