# CVE-2026-55877: Symfony UX Icons cross-site scripting via unsanitized SVG content

Source: https://junglewise.ai/threats/cve-2026-55877-symfony-ux-icons-cross-site-scripting-via-unsanitized-svg-content  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-07-08. Updated: 2026-07-08  
License: CC BY 4.0 with a link back

CVE-2026-55877 · Severity: medium · CVSS 6.1 · Published 2026-07-08

Symfony UX Icons is a library used to integrate icons into Symfony web applications. A security flaw allows malicious code hidden within SVG icon files or remote icon services to be executed in a user's browser. This could lead to cross-site scripting (XSS) attacks, potentially allowing an attacker to steal user sessions or perform unauthorized actions on behalf of users.

Vendors: [Packagist](https://junglewise.ai/threats/vendors/packagist), [Symfony](https://junglewise.ai/threats/vendors/symfony).

## Quick answers

**Is CVE-2026-55877 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-55877 being exploited in the wild.

**How severe is CVE-2026-55877?** Medium severity, with a CVSS score of 6.1, published 8 July 2026.

**Which products and versions are affected?** symfony/ux-icons (Packagist) ECOSYSTEM:introduced=2.17.0,fixed=2.36.1; Symfony UX Icons >= 2.17.0, < 2.36.1; >= 3.0.0, < 3.2.0.

**Is there a fix for CVE-2026-55877?** Yes. symfony/ux-icons (Packagist): upgrade to 2.36.1 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-55877 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-55877?** Check whether you run symfony/ux-icons (Packagist) or Symfony UX Icons at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- symfony/ux-icons (Packagist): upgrade to 2.36.1 or later

  ```sh
  composer require symfony/ux-icons:^2.36.1
  ```


## Technical details

A cross-site scripting (XSS) vulnerability exists in the ux_icon() Twig function of Symfony UX Icons. The function is marked as 'is_safe=html', and the Icon::toHtml() method inlines SVG source code verbatim without adequate sanitization. This allows malicious SVG files (either stored locally or fetched from a remote Iconify endpoint) containing script elements, event handlers (on*), or dangerous URL schemes to execute JavaScript in the context of the user's browser. The issue stems from incomplete sanitization in Icon::fromFile() and a total lack of sanitization for Iconify JSON responses. The fix introduces an IconFactory that centralizes sanitization, stripping dangerous elements like <script>, <foreignObject>, and <iframe before icon creation.

## Affected products

- Symfony ux-icons >= 2.17.0, < 2.36.1; >= 3.0.0, < 3.2.0

## Identifiers

- CVE-2026-55877
- GHSA-6v8j-33hc-mv84

## Timeline

- 2026-06-19: patched: Fixes released in versions 2.36.1 and 3.2.0
- 2026-07-08: disclosed: CVE-2026-55877 published

## References

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