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

Quick assessment

Affected
symfony ux
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Symfony ux是Symfony组织开源的一个Symfony的JavaScript生态系统。 Symfony UX存在跨站脚本漏洞，该漏洞源于ux_icon() Twig函数被标记为 is_safe=['html'] 且 Icon::toHtml() 直接内联SVG源代码，导致未清理的本地SVG文件或Iconify按需JSON正文响应中包含嵌套脚本元素、on*事件处理程序或危险URL方案，容易受到跨站脚本攻击。以下版本受到影响：2.17.0版本至2.36.1之前版本和3.0.0版本至3.2.0之前版本

CVSS 6.1 · Medium EPSS 0.34% · P27

Possible ATT&CK Techniques 1 AI

T1059 · Command and Scripting Interpreter

Affected Version Matrix 2

VendorProduct Version RangeStatus
symfony ux >= 2.17.0, < 2.36.1 affected
>= 3.0.0, < 3.2.0 affected
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I. Basic Information for CVE-2026-55877

Vulnerability Information
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Vulnerability Title
Symfony UX: XSS in symfony/ux-icons via unsanitized SVG content in local files and Iconify on-demand responses
Source: CVE Program / CVE List V5
Vulnerability 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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
Source: CVE Program / CVE List V5
Vulnerability Type
在Web页面生成时对输入的转义处理不恰当(跨站脚本)
Source: CVE Program / CVE List V5
Vulnerability Title
Symfony UX 跨站脚本漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Symfony ux是Symfony组织开源的一个Symfony的JavaScript生态系统。 Symfony UX存在跨站脚本漏洞，该漏洞源于ux_icon() Twig函数被标记为 is_safe=['html'] 且 Icon::toHtml() 直接内联SVG源代码，导致未清理的本地SVG文件或Iconify按需JSON正文响应中包含嵌套脚本元素、on*事件处理程序或危险URL方案，容易受到跨站脚本攻击。以下版本受到影响：2.17.0版本至2.36.1之前版本和3.0.0版本至3.2.0之前版本
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
symfony ux >= 2.17.0, < 2.36.1 -

II. Public POCs for CVE-2026-55877

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III. Intelligence Information for CVE-2026-55877

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Vendor Advisories for CVE-2026-55877 (1)

Vendor Pages for CVE-2026-55877 (2)

IV. Related Vulnerabilities

Same product: ux
Same vendor: symfony
Same weakness: CWE-79