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CVE-2026-109869— undici vulnerable to Denial of Service via unhandled error on excessive content-encodings

Quick assessment

Affected
undici undici
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.

undici 是 Node.js 的一个 HTTP 客户端库。在版本 6.23.0 至 6.29.0、7.18.0 至 7.30.0，以及 8.0.0 至 8.12.1 中，当恶意服务器返回包含超过五种内容编码（content codings）的响应，并在发送响应体之前关闭连接时，其 实现会导致 Node.js 进程崩溃。 undici 本身因内容编码数量限制而拒绝此类响应，但在执行该检查之前，它已经创建了内部响应流，并且在返回时未附加错误监听器或中止请求。因此，连接的过早关闭会在孤立（orphaned）的响应流上

CVSS 7.5 · High

Possible ATT&CK Techniques 1 AI

T1499 · Endpoint Denial of Service

Affected Version Matrix 6

VendorProduct Version RangeStatus
undici undici 6.23.0< 6.29.1 affected
6.29.1 unaffected
7.18.0< 7.30.1 affected
7.30.1 unaffected
8.0.0< 8.12.2 affected
8.12.2 unaffected
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I. Basic Information for CVE-2026-109869

Vulnerability Information
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Vulnerability Title
undici vulnerable to Denial of Service via unhandled error on excessive content-encodings
Source: CVE Program / CVE List V5
Vulnerability Description
undici is an HTTP client library for Node.js. In versions 6.23.0 through 6.29.0, 7.18.0 through 7.30.0, and 8.0.0 through 8.12.1, its fetch() implementation crashes the Node.js process when a malicious server returns a response with more than five content codings and closes the connection before sending the body. undici rejects such responses because of a content-encoding limit, but it created the internal response stream before that check and returned without attaching an error listener or aborting the request, so the early close surfaces a content-length mismatch on the orphaned stream, which Node.js treats as an unhandled error and terminates the process. A remote, unauthenticated server can trigger this with a single response, even when the application correctly catches the fetch() rejection, resulting in a denial of service. The issue is fixed in undici 6.29.1, 7.30.1, and 8.12.2, and users should upgrade to one of those versions or later. There is no workaround.
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
undici undici 6.23.0 ~ 6.29.1 -

II. Public POCs for CVE-2026-109869

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III. Intelligence Information for CVE-2026-109869

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Vendor Advisories for CVE-2026-109869 (1)

Same Patch Batch · undici · 2026-10-15 · 9 CVEs total

CVE-2026-109855 7.5 HIGH undici WebSocket client vulnerable to Denial of Service via failed HTTP/2 handshake
CVE-2026-87018 7.5 HIGH undici vulnerable to Denial of Service via TLS 1.2 certificate-changing renegotiation
CVE-2026-109383 7.4 HIGH undici vulnerable to TLS certificate validation bypass via dropped tls options in Agent
CVE-2026-109829 7.4 HIGH undici vulnerable to cache poisoning and cross-user disclosure via cross-origin redirects
CVE-2026-87029 5.9 MEDIUM undici vulnerable to Denial of Service via unhandled exception in the decompress intercept
CVE-2026-109932 5.9 MEDIUM undici WebSocket client vulnerable to Denial of Service via unbounded automatic PONG buffe
CVE-2026-109841 5.9 MEDIUM undici vulnerable to Subresource Integrity bypass via non-lowercase algorithm tokens
CVE-2026-109924 5.9 MEDIUM undici vulnerable to Denial of Service via unbounded memory in the EventSource parser

IV. Related Vulnerabilities

Same product: undici
Same vendor: undici
Same weakness: CWE-248

V. Comments for CVE-2026-109869

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