CVE-2026-31823: Sylius has Authenticated Stored XSS

Impact

An authenticated stored cross-site scripting (XSS) vulnerability exists in multiple places across the shop frontend and admin panel due to unsanitized entity names being rendered as raw HTML.

Shop breadcrumbs (shared/breadcrumbs.html.twig): The breadcrumbs macro uses the Twig |raw filter on label values. Since taxon names, product names, and ancestor names flow directly into these labels, a malicious taxon name like <img src=x onerror=alert('XSS')> is rendered and executed as JavaScript on the storefront.

Admin product taxon picker (ProductTaxonTreeController.js): The rowRenderer method interpolates ${name} directly into a template literal building HTML, allowing script injection through taxon names in the admin panel.

Admin autocomplete fields (Tom Select): Dropdown items and options render entity names as raw HTML without escaping, allowing XSS through any autocomplete field displaying entity names.

An authenticated administrator can inject arbitrary HTML or JavaScript via entity names (e.g. taxon name) that is persistently rendered for all users.

Patches

The issue is fixed in versions: 2.0.16, 2.1.12, 2.2.3 and above.

Workarounds

Override vulnerable templates and JavaScript controllers at the project level.

---

Step 1 — Override shop breadcrumbs template

templates/bundles/SyliusShopBundle/shared/breadcrumbs.html.twig:

twig {% macro breadcrumbs(items) %} <ol class="breadcrumb" aria-label="breadcrumbs"> {% for item in items %} <li class="breadcrumb-item fw-normal{{ item.active is defined and item.active ? ' active' }}"> {% if item.path is defined %} <a class="link-reset" href="{{ item.path }}" {{ item.testattribute is defined ? syliustesthtmlattribute(item.testattribute) }}>{{ item.label }}</a> {% else %} <span class="text-body-tertiary text-break" {{ item.testattribute is defined ? syliustesthtmlattribute(item.testattribute) }}>{{ item.label }}</span> {% endif %} </li> {% endfor %} </ol> {% endmacro %}

Step 2 — Override order breadcrumbs template

templates/bundles/SyliusShopBundle/account/order/show/content/breadcrumbs.html.twig:

twig {% from '@SyliusShop/shared/breadcrumbs.html.twig' import breadcrumbs as breadcrumbs %}

{% set order = hookablemetadata.context.order %}

<div class="col-12"> {{ breadcrumbs([ { label: 'sylius.ui.home'|trans, path: path('syliusshophomepage')}, { label: 'sylius.ui.myaccount'|trans, path: path('syliusshopaccountdashboard')}, { label: 'sylius.ui.orderhistory'|trans, path: path('syliusshopaccountorderindex')}, { label: '#'~order.number, active: true, testattribute: 'order-number' } ]) }} </div>

Step 3 — Override ProductTaxonTreeController.js

Disable the vendor controller in assets/admin/controllers.json:

diff "product-taxon-tree": { - "enabled": true, + "enabled": false, "fetch": "lazy" },

Create assets/admin/controllers/producttaxontreecontroller.js — copy the original from vendor/sylius/sylius/src/Sylius/Bundle/AdminBundle/Resources/assets/controllers/ProductTaxonTreeController.js and apply the following change:

diff + const escapeHtml = (str) => { + const div = document.createElement('div'); + div.textContent = str; + return div.innerHTML; + };

// in rowRenderer: - <span class="infinite-tree-title">${name}</span> + <span class="infinite-tree-title">${escapeHtml(name)}</span>

Register the patched controller in assets/admin/bootstrap.js:

js import ProductTaxonTreeController from './controllers/producttaxontreecontroller'; app.register('sylius--admin-bundle--product-taxon-tree', ProductTaxonTreeController);

Step 4 — Add autocomplete XSS protection

assets/admin/scripts/autocomplete-xss-protection.js:

js const escapeHtml = (str) => { if (typeof str !== 'string') return str; const div = document.createElement('div'); div.textContent = str; return div.innerHTML; };

document.addEventListener('autocomplete:pre-connect', (event) => { const options = event.detail.options; if (!options.render) return;

const labelField = options.labelField || 'text'; const wrapRenderer = (renderer) => { if (!renderer) return renderer; return (data, escape) => { const escaped = { ...data }; if (escaped[labelField]) { escaped[labelField] = escapeHtml(escaped[labelField]); } return renderer(escaped, escape); }; };

if (options.render.item) options.render.item = wrapRenderer(options.render.item); if (options.render.option) options.render.option = wrapRenderer(options.render.option); });

Import in assets/admin/entrypoint.js before bootstrap:

diff + import './scripts/autocomplete-xss-protection'; import './bootstrap.js';

Step 5 — Rebuild assets

bash yarn encore dev # or: yarn encore production

Reporters

We would like to extend our gratitude to the following individuals for their detailed reporting and responsible disclosure of this vulnerability: - Djibril Mounkoro (@whiteov3rflow) - Bartłomiej Nowiński (@bnBart)

For more information

If you have any questions or comments about this advisory:

- Open an issue in Sylius issues - Email us at security@sylius.com