GHSA-4J38-F5CW-54H7
Vulnerability from github – Published: 2026-05-21 21:21 – Updated: 2026-05-21 21:21
VLAI
Summary
Twig: The `spaceless` filter implicitly marks its output as safe
Details
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:
{% 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.
Severity
{
"affected": [
{
"package": {
"ecosystem": "Packagist",
"name": "twig/twig"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "3.26.0"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2026-46628"
],
"database_specific": {
"cwe_ids": [
"CWE-116"
],
"github_reviewed": true,
"github_reviewed_at": "2026-05-21T21:21:35Z",
"nvd_published_at": null,
"severity": "LOW"
},
"details": "### Description\n\nThe `spaceless` filter is registered with `is_safe =\u003e [\u0027html\u0027]`, which means Twig\u0027s 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 = \u0027\u003cscript\u003ealert()\u003c/script\u003e\u0027 %}\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.",
"id": "GHSA-4j38-f5cw-54h7",
"modified": "2026-05-21T21:21:35Z",
"published": "2026-05-21T21:21:35Z",
"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"
}
],
"schema_version": "1.4.0",
"severity": [
{
"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",
"type": "CVSS_V4"
}
],
"summary": "Twig: The `spaceless` filter implicitly marks its output as safe"
}
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Experimental. This forecast is provided for visualization only and may change without notice. Do not use it for operational decisions.
Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the
vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base
model, served locally by ML-Gateway.
They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
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Related by attack behaviour
Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.
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