CVE-2026-46628: Twig The `spaceless` Filter Implicitly Marks Vulnerability

LOW
Advisory Identifier: GHSA-4j38-f5cw-54h7
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CWE-116
Published
Advisory Summary

CVE-2026-46628 is a LOW the `spaceless` filter implicitly marks vulnerability (CWE-116: Improper Encoding or Escaping of Output) affecting Twig libraries in the Packagist ecosystem. The issue involves the `spaceless` filter implicitly marks its output as safe. Remediation is available by upgrading affected packages to version 3.26.0.

CVE-2026-46628 at a Glance

CVE Identifier CVE-2026-46628
GHSA Identifier GHSA-4j38-f5cw-54h7
Severity LOW
CVSS v3.1 Base Score N/A
CWE Classification CWE-116: Improper Encoding or Escaping of Output
Affected Product Twig
Package Ecosystem Packagist
Published Date
Last Updated

How to Fix CVE-2026-46628

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

twig/twig fixed: 3.26.0 
Upgrade twig/twig to 3.26.0
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 twig/twig

How to Check if You Are Affected

To determine whether your application is affected by CVE-2026-46628, inspect your project dependencies for Twig:

inspect dependencies for twig/twig

Analyze the terminal output to locate any version of Twig in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 3.26.0), 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-116: Improper Encoding or Escaping of Output, where the product prepares a structured message for communication with another component, but encoding or escaping of the data is either missing or done incorrectly. as a result, the intended structure of the message is not preserved. In Twig, 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

### Description The `spaceless` filter is registered with `is_safe => ['html']`, which means Twig's autoescaper does not escape its output in an HTML context. As a result, applying `spaceless` to attacker-controlled input that contains markup emits the markup unescaped even when the developer never wrote `|raw` and autoescape is enabled. Example: ```twig {% set payload = '<script>alert()</script>' %} {{ payload }} {# escaped #} {{ payload|spaceless }} {# not escaped #} ``` The filter is deprecated but still functional. With the deprecation, some downstream projects (e.g. Drupal modules) have duplicated the filter and inherited the same `is_safe` flag. ### Resolution The `spaceless` filter no longer marks its output as safe. Documentation has been updated to warn that `spaceless` should not be applied to unsanitised user input. ### Credits Twig would like to thank Pierre Rudloff for reporting the issue.

CVE-2026-46628 Affected Twig Versions

1 component(s)
Fixed Versions:
3.26.0
Product / Package Ecosystem Affected Versions Fixed Version
twig/twig
 Packagist
< 3.26.0
3.26.0

References

GitHub Advisory / Wiki ADVISORY
https://github.com/twigphp/Twig/security/advisories/GHSA-4j38-f5cw-54h7
Twig Source Repository REPOSITORY
https://github.com/FriendsOfPHP/security-advisories/blob/master/twig/twig/CVE-2026-46628.yaml
Twig Source Repository REPOSITORY
https://github.com/twigphp/Twig
symfony.com/cve-2026-46628 WEB
https://symfony.com/cve-2026-46628

Frequently Asked Questions

What is CVE-2026-46628?
CVE-2026-46628 is a security vulnerability in Twig involving The `spaceless` filter implicitly marks its output as safe under CWE-116: Improper Encoding or Escaping of Output.
Which Twig versions are affected?
Affected versions include releases prior to 3.26.0 across affected packages: twig/twig.
What version fixes CVE-2026-46628?
Upgrading to 3.26.0 (or the latest patched release for your respective branch) resolves the vulnerability.
Is twig/twig affected?
Yes, twig/twig is affected in releases prior to 3.26.0. Upgrade your dependency to 3.26.0 or later.
What CWE is associated with CVE-2026-46628?
CVE-2026-46628 is classified under CWE-116: Improper Encoding or Escaping of Output (The product prepares a structured message for communication with another component, but encoding or escaping of the data is either missing or done incorrectly. As a result, the intended structure of the message is not preserved.).
How can I check Packagist dependencies for CVE-2026-46628?
Run the dependency tree command: 'inspect dependencies for twig/twig'. 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-4j38-f5cw-54h7",
  "modified" : "2026-05-21T21:21:35Z",
  "published" : "2026-05-21T21:21:35Z",
  "aliases" : [ "CVE-2026-46628" ],
  "summary" : "Twig: The `spaceless` filter implicitly marks its output as safe",
  "details" : "### Description\n\nThe `spaceless` filter is registered with `is_safe => ['html']`, which means Twig's autoescaper does not escape its output in an HTML context. As a result, applying `spaceless` to attacker-controlled input that contains markup emits the markup unescaped even when the developer never wrote `|raw` and autoescape is enabled.\n\nExample:\n\n```twig\n{% set payload = '<script>alert()</script>' %}\n{{ payload }}          {# escaped #}\n{{ payload|spaceless }} {# not escaped #}\n```\n\nThe filter is deprecated but still functional. With the deprecation, some downstream projects (e.g. Drupal modules) have duplicated the filter and inherited the same `is_safe` flag.\n\n### Resolution\n\nThe `spaceless` filter no longer marks its output as safe. Documentation has been updated to warn that `spaceless` should not be applied to unsanitised user input.\n\n### Credits\n\nTwig would like to thank Pierre Rudloff for reporting the issue.",
  "severity" : [ {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N/E:U"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Packagist",
      "name" : "twig/twig"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "3.26.0"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/twigphp/Twig/security/advisories/GHSA-4j38-f5cw-54h7"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/FriendsOfPHP/security-advisories/blob/master/twig/twig/CVE-2026-46628.yaml"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/twigphp/Twig"
  }, {
    "type" : "WEB",
    "url" : "https://symfony.com/cve-2026-46628"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-116" ],
    "severity" : "LOW",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-05-21T21:21:35Z",
    "nvd_published_at" : null
  }
}