What is CVE-2026-46637?

CVE-2026-46637 is a medium-severity vulnerability in Symfony Twig, classified under Improper Encoding or Escaping of Output. CVSS score: 5.4/10. Published 2026-07-14.

How severe is CVE-2026-46637?

Medium severity. CVSS v3 base score is 5.4 out of 10.

XSS in Symfony Twig

CVE-2026-46637

Twig is a template language for PHP. Prior to 3.26.0, several filters in twig/markdown-extra and twig/cssinliner-extra are registered with is_safe => [all], causing Twig to treat plain text or HTML output as safe in HTML, JavaScript, CSS, URL, and other contexts where the output is not properly escaped. This issue is fixed in version 3.26.0.

Published 2026-07-14 · last modified 2026-07-16.

CVSS v3 metric

CVSS v3 base score 5.4 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N.

EPSS exploit prediction

EPSS: 0.003 (22.1th percentile), scored 2026-10-24.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 22nd percentile — 22.1% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.003 · newest: 0.003 · change: 0.000

Affected products

Symfony Twig
Twig Cssinliner-Extra — versions < 3.26.0
Twig Markdown-Extra — versions < 3.26.0
Twigphp Twig — versions < 3.26.0

Weakness classification (CWE)

References

github.com/twigphp/Twig/security/advisories/GHSA-jv8m-2544-3pg3 (Vendor Advisory)
github.com/twigphp/Twig/commit/84982072c79a7417b0d158a401d91344f3658299 (Patch)
github.com/twigphp/Twig/commit/e36489d3521ecbfc08bdcc61294302557035f14a (Patch)
github.com/twigphp/Twig/releases/tag/v3.26.0 (Release Notes)

Frequently asked questions

What is CVE-2026-46637?: CVE-2026-46637 is a medium-severity vulnerability in Symfony Twig, classified under Improper Encoding or Escaping of Output. CVSS score: 5.4/10. Published 2026-07-14.
How severe is CVE-2026-46637?: Medium severity. CVSS v3 base score is 5.4 out of 10.