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CVE-2026-49209— Symfony UX: Denial of service in symfony/ux-live-component via unbounded batch action requests

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 2.5.0版本至2.36.0之前版本和3.1.0版本存在资源管理错误漏洞，该漏洞源于客户端提供的动作数组大小不受限制，可能导致通过身份验证的客户端发起包含数千个动作的_batch请求，从而耗尽应用服务器的CPU、内存和数据库连接。

AI Predicted 5.3 Difficulty: Easy EPSS 0.56% · P45

Possible ATT&CK Techniques 1 AI

T1496 · Resource Hijacking

Affected Version Matrix 2

VendorProduct Version RangeStatus
symfony ux >= 3.0.0, < 3.1.0 affected
>= 2.5.0, < 2.36.0 affected
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I. Basic Information for CVE-2026-49209

Vulnerability Information
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Vulnerability Title
Symfony UX: Denial of service in symfony/ux-live-component via unbounded batch action requests
Source: CVE Program / CVE List V5
Vulnerability Description
Symfony UX is a JavaScript ecosystem for Symfony. From 2.5.0 until 2.36.0 and 3.1.0, Symfony\UX\LiveComponent\Controller\BatchActionController::__invoke() iterates over the client-supplied actions array and issues a full HttpKernel sub-request for each entry; because the array size is never bounded, an authenticated client can submit a single _batch request containing thousands of actions and exhaust CPU, memory, and database connections on the application server. This issue is fixed in versions 2.36.0 and 3.1.0.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N
Source: CVE Program / CVE List V5
Vulnerability Type
不加限制或调节的资源分配
Source: CVE Program / CVE List V5
Vulnerability Title
Symfony UX 资源管理错误漏洞
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 2.5.0版本至2.36.0之前版本和3.1.0版本存在资源管理错误漏洞，该漏洞源于客户端提供的动作数组大小不受限制，可能导致通过身份验证的客户端发起包含数千个动作的_batch请求，从而耗尽应用服务器的CPU、内存和数据库连接。
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 >= 3.0.0, < 3.1.0 -

II. Public POCs for CVE-2026-49209

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III. Intelligence Information for CVE-2026-49209

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Patches & Fixes for CVE-2026-49209 (3)

Vendor Advisories for CVE-2026-49209 (1)

Same Patch Batch · symfony · 2026-07-17 · 7 CVEs total

CVE-2026-49210 Symfony UX: XSS in symfony/ux-live-component via attacker-controlled child component tag
CVE-2026-49215 Symfony UX: CSRF Protection Bypass in symfony/ux-live-component — Accept Header is CORS-Sa
CVE-2026-49208 Symfony UX: Format-less date LiveProps parsed with the permissive DateTime constructor
CVE-2026-49212 Symfony UX: LiveComponentHydrator HMAC checksum lacks component and slot binding
CVE-2026-49216 Symfony UX: XSS in symfony/ux-autocomplete via unescaped AJAX response data
CVE-2026-49211 Symfony UX: Information exposure via unescaped LIKE wildcards in EntitySearchUtil

IV. Related Vulnerabilities

Same product: ux
Same vendor: symfony
Same weakness: CWE-770

V. Comments for CVE-2026-49209

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