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CVE-2026-109932— undici WebSocket client vulnerable to Denial of Service via unbounded automatic PONG buffering

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 HTTP 客户端库。在版本 5.15.0 至 6.29.0、7.0.0 至 7.30.0 以及 8.0.0 至 8.12.1 中，其 WebSocket 客户端（包括 Node.js 内置暴露的 WebSocket 实现）可能被恶意或已受 compromise 的 WebSocket 服务器利用，导致进程内存耗尽。具体而言，每当客户端接收到一个 PING 帧时，会自动写入对应的 PONG 响应，并忽略来自 socket 写入操作的背压（backpressure）信号。因此，如果

CVSS 5.9 · Medium

Possible ATT&CK Techniques 1 AI

T1499 · Endpoint Denial of Service

Affected Version Matrix 6

VendorProduct Version RangeStatus
undici undici 5.15.0< 6.29.1 affected
6.29.1 unaffected
7.0.0< 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-2026-109932

Vulnerability Information
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Vulnerability Title
undici WebSocket client vulnerable to Denial of Service via unbounded automatic PONG buffering
Source: CVE Program / CVE List V5
Vulnerability Description
undici is an HTTP client library for Node.js. In versions 5.15.0 through 6.29.0, 7.0.0 through 7.30.0, and 8.0.0 through 8.12.1, its WebSocket client, including the bundled WebSocket exposed by Node.js, can be driven to exhaust process memory by a malicious or compromised WebSocket server. For every PING frame received, the client automatically writes a PONG response and ignores the backpressure signal from the socket write, so a server that streams small PING frames while never reading the client's PONGs makes the outbound write queue and heap grow without bound until the Node.js process runs out of memory and terminates. The attack is remote and unauthenticated, needs only a normal WebSocket connection, and is asymmetric, since small inbound PINGs produce a much larger retained outbound queue, with availability the only impact. The issue is fixed in undici 6.29.1, 7.30.1, and 8.12.2, which pause WebSocket frame parsing when the automatic PONG response hits socket backpressure and resume on drain, bounding the outbound queue, 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:H/PR:N/UI:N/S:U/C:N/I:N/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
未加控制的资源消耗(资源穷尽)
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
undici undici 5.15.0 ~ 6.29.1 -

II. Public POCs for CVE-2026-109932

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III. Intelligence Information for CVE-2026-109932

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Vendor Advisories for CVE-2026-109932 (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-2026-109869 7.5 HIGH undici vulnerable to Denial of Service via unhandled error on excessive content-encodings
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-2026-109841 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-400

V. Comments for CVE-2026-109932

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