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CVE-2026-84942— Stored Cross-Site Scripting via Vega Expression Function Bypass in OpenSearch Dashboards

Quick assessment

Affected
AWS Amazon OpenSearch Service
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.

OpenSearch Dashboards 中 Vega 表达式函数实现存在输入验证不当的问题。这允许拥有仪表盘写入权限的远程认证用户在保存一个经过构造的 Vega 可视化图表时，在其他用户的浏览器会话上下文中执行任意 JavaScript 代码。 验证例程未能递归处理对象数组，导致嵌套在数组内部的函数属性得以绕过验证。

CVSS 8.7 · High EPSS 0.33% · P26

Possible ATT&CK Techniques 1 AI

T1059 · Command and Scripting Interpreter

Affected Version Matrix 2

VendorProduct Version RangeStatus
AWS Amazon OpenSearch Service v2.3.0≤ v3.5.0 unaffected
OpenSearch OpenSearch Dashboards v2.0.0≤ v3.5.0 affected
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I. Basic Information for CVE-2026-84942

Vulnerability Information
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Vulnerability Title
Stored Cross-Site Scripting via Vega Expression Function Bypass in OpenSearch Dashboards
Source: CVE Program / CVE List V5
Vulnerability Description
Improper input validation in the Vega expression function implementation in OpenSearch Dashboards allows a remote authenticated actor with dashboard write permissions to execute arbitrary JavaScript in the context of other users' browser sessions by saving a crafted Vega visualization. The checkForFunctionProperty validation routine failed to recurse into arrays of objects, allowing a function property nested inside an array to bypass validation.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/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

Affected Products

Vendor Product Affected Versions CPE Subscribe
AWS Amazon OpenSearch Service - -
OpenSearch OpenSearch Dashboards v2.0.0 ~ v3.5.0 -

II. Public POCs for CVE-2026-84942

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III. Intelligence Information for CVE-2026-84942

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Vendor Advisories for CVE-2026-84942 (1)

Vendor Pages for CVE-2026-84942 (2)

IV. Related Vulnerabilities

Same product: Amazon OpenSearch Service
Same vendor: AWS
Same weakness: CWE-79

V. Comments for CVE-2026-84942

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