CVE-2026-55877
MediumCVSS 6.1Exploitation Probability (EPSS)
Low risk9th percentile - higher than 9% of all known CVEs
Summary
A vulnerability in Symfony UX allows XSS via the ux_icon() Twig function, which marks output as safe (is_safe=['html']) and embeds SVG source verbatim. Unsanitized local SVG files or Iconify JSON responses can contain malicious scripts, event handlers, or dangerous URL schemes.
Risk Assessment
An attacker can inject malicious JavaScript into the page, leading to session theft, redirects, or content manipulation visible to users.
Recommendation
Upgrade Symfony UX to version 2.36.1 or 3.2.0 immediately, which contain the fix for this vulnerability.
Other vulnerabilities in Symfony UX
See all- CVE-2026-49215Medium
A vulnerability in Symfony UX allows CSRF attacks on LiveComponent components. The protection mechanism relies on the Accept header, which can be set by an attacker in a cross-origin request without preflight, enabling unauthorized actions on a victim's session.
- CVE-2026-49212High
A vulnerability in Symfony UX allows an attacker to swap a signed data blob between components or slots, enabling the setting of read-only properties on a target component. Affected versions are from 2.8.0 to 2.36.0 and 3.1.0.
- CVE-2026-49211High
A vulnerability in Symfony UX allows unauthenticated users to turn the public autocomplete endpoint into a broad matcher or blind boolean oracle. The issue is due to missing escaping of SQL LIKE wildcards (% , _ , \) in the client-supplied query.
- CVE-2026-49210Medium
A vulnerability in Symfony UX allows arbitrary HTML injection, including <script> tags, during Live Component re-rendering. The client-controlled children[id].tag value is interpolated directly into HTML without escaping or validation.
- CVE-2026-49209Medium
A vulnerability in Symfony UX allows an authenticated client to send a single _batch request with thousands of actions, exhausting server resources (CPU, memory, database connections) due to unbounded iteration over the actions array.
- CVE-2026-49208Medium
A vulnerability in Symfony UX allows an attacker to manipulate dates by sending relative strings (e.g., now, tomorrow, +10 years) to a LiveProp of type DateTimeInterface without a configured format. This bypasses time-based business logic checks.
- CVE-2026-55878High
A vulnerability in Symfony UX allows writing files to arbitrary locations or reading local files outside the recipe directory via a crafted recipe kit. The issue affects the ux:install console command which uses Path::isRelative() accepting paths like ../../../etc.
Original NVD description (English source)
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.