What is CVE-2026-45753?

CVE-2026-45753 is a medium-severity vulnerability in Sensiolabs Symfony, classified under Cross-site Scripting. CVSS score: 6.1/10. Published 2026-07-14.

How severe is CVE-2026-45753?

Medium severity. CVSS v3 base score is 6.1 out of 10.

XSS in Sensiolabs Symfony

CVE-2026-45753

Symfony is a PHP framework for web and console applications and a set of reusable PHP components. From 6.1.0-BETA1 until 6.4.40, 7.4.12, and 8.0.12, UrlAttributeSanitizer::getSupportedAttributes() omits URL-valued attributes including action, formaction, poster, and cite, so configurations that admit those attributes can leave javascript: URIs unsanitized and enable XSS when the resulting HTML is rendered or a victim submits a form or clicks a button. This issue is fixed in versions 6.4.40, 7.4.12, and 8.0.12.

Vulnerability class: XSS (Cross-Site Scripting)

Published 2026-07-14 · last modified 2026-07-15.

CVSS v3 metric

CVSS v3 base score 6.1 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N.

EPSS exploit prediction

EPSS: 0.003 (25.3th percentile), scored 2026-10-13.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 25th percentile — 25.3% 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

Sensiolabs Symfony
Symfony Html-Sanitizer — versions >= 6.1.0-BETA1, < 6.4.40, >= 7.0.0-BETA1, < 7.4.12, >= 8.0.0-BETA1, < 8.0.12
Symfony — versions >= 6.1.0-BETA1, < 6.4.40, >= 7.0.0-BETA1, < 7.4.12, >= 8.0.0-BETA1, < 8.0.12

Weakness classification (CWE)

References

github.com/symfony/symfony/security/advisories/GHSA-hhg7-c65m-h7ff (Patch, Vendor Advisory)
github.com/symfony/symfony/commit/487728e7e180a674a6d4c01bd0cb56161cc441b7 (Patch)
github.com/symfony/symfony/releases/tag/v6.4.40 (Product, Release Notes)
github.com/symfony/symfony/releases/tag/v7.4.12 (Product, Release Notes)
github.com/symfony/symfony/releases/tag/v8.0.12 (Product, Release Notes)

Frequently asked questions

What is CVE-2026-45753?: CVE-2026-45753 is a medium-severity vulnerability in Sensiolabs Symfony, classified under Cross-site Scripting. CVSS score: 6.1/10. Published 2026-07-14.
How severe is CVE-2026-45753?: Medium severity. CVSS v3 base score is 6.1 out of 10.