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CVE-2026-42270— countly-server: Unauthenticated Denial of Service (DoS) via Unhandled Stream Exception

Quick assessment

Affected
Countly countly-server
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.

Countly-server 是 Countly（一款产品分析解决方案）的服务器端组件。在版本 24.05.50 和 25.03.44 之前， 和 等公开的图片与截图路由在使用本地文件系统（fs）存储后端时，会调用 并将文件系统流直接管道化到 HTTP 响应中，但未添加错误监听器。未经身份验证的请求若包含 URL 编码的句点（ ），可导致 尝试打开目录，从而触发异步的 错误；由于该错误未被处理，Node.js 进程将因未捕获异常而终止。攻击者可通过重复发送此类请求，使分析 API 持续不可用。受影响的路线还包括 、

CVSS 7.5 · High

Possible ATT&CK Techniques 1 AI

T1499 · Endpoint Denial of Service

Affected Version Matrix 2

VendorProduct Version RangeStatus
Countly countly-server < 24.05.50 affected
>= 25.03, < 25.03.44 affected
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I. Basic Information for CVE-2026-42270

Vulnerability Information
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Vulnerability Title
countly-server: Unauthenticated Denial of Service (DoS) via Unhandled Stream Exception
Source: CVE Program / CVE List V5
Vulnerability Description
countly-server is the server-side part of Countly, a product analytics solution. Prior to 24.05.50 and 25.03.44, star-rating/images/ and dashboards/images/screenshots/ are among public image and screenshot routes using the local fs storage backend that call getStream and pipe filesystem streams to HTTP responses without an error listener. An unauthenticated request containing a URL-encoded dot can make createReadStream open a directory, emit an asynchronous EISDIR error, and terminate the Node.js process as an unhandled exception, allowing repeated requests to keep the analytics API unavailable. The affected routes also include /appimages/*, /memberimages/*, and */screenshots/*. This issue is fixed in versions 24.05.50 and 25.03.44.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
未捕获的异常
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
Countly countly-server < 24.05.50 -

II. Public POCs for CVE-2026-42270

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III. Intelligence Information for CVE-2026-42270

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Patches & Fixes for CVE-2026-42270 (2)

Vendor Advisories for CVE-2026-42270 (1)

Vendor Pages for CVE-2026-42270 (2)

Same Patch Batch · Countly · 2026-10-16 · 4 CVEs total

CVE-2026-44977 9.0 CRITICAL countly-server: Stored XSS in feedback upload enables app-admin to compromise global admin
CVE-2026-42269 8.1 HIGH countly-server: Path Traversal in delete_import Endpoint Allows Arbitrary File and Directo
CVE-2026-41582 7.5 HIGH countly-server: Unauthenticated Path Traversal via Public Image and Screenshot Routes Lead

IV. Related Vulnerabilities

Same product: countly-server
Same vendor: Countly
Same weakness: CWE-248

V. Comments for CVE-2026-42270

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