What’s Vulnerable › Vulnerabilities

CVE-2026-55877: Symfony UX: XSS in symfony/ux-icons via unsanitized SVG content in local files and Iconify on-demand responses

• Severity: medium (CVSS 6.1 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.3% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-07-08 · updated 2026-10-25
• Weakness: CWE-79

Description

Symfony UX is a JavaScript ecosystem for Symfony. From 2.17.0 before 2.36.1 and from 3.0.0 before 3.2.0, the ux_icon() Twig function is marked is_safe=['html'] and Icon::toHtml() inlines SVG source verbatim, allowing unsanitized local SVG files or Iconify on-demand JSON body responses containing nested script elements, on* event handlers, or dangerous URL schemes to execute cross-site scripting. This issue is fixed in versions 2.36.1 and 3.2.0.

Affected products

• symfony ux: from 2.17.0 before 2.36.1; from 3.0.0 before 3.2.0 — fixed in 2.36.1, 3.2.0

How to fix

Upgrade to a fixed version: symfony ux 2.36.1, 3.2.0. Check the vendor advisory for mitigations.

References

• https://github.com/symfony/ux/commit/3a4964ec3700f0af4e13f7bfbf8bb3174c3e79d1
• https://github.com/symfony/ux/releases/tag/v2.36.1
• https://github.com/symfony/ux/releases/tag/v3.2.0
• https://github.com/symfony/ux/security/advisories/GHSA-6v8j-33hc-mv84

Get alerted when CVE-2026-55877 or the next vulnerability affects your stack