Live › vulnerability › CVE-2026-109924
Go to dashboardThe undici HTTP client for Node.js keeps growing parser state while reading Server-Sent Events, so a malicious or compromised SSE server can drive memory use up. A small compressed response can expand into enough retained memory to crash the process, which is a denial of service with no code execution.
Summary written from the sources below. Check the originals before acting.
First seen by InfraStack 2026-10-23 22:15 UTC, 1h before NVD. All times on this page are UTC.
Applications that open an EventSource connection with undici to a server they do not fully trust, such as third-party streams, webhooks or remote APIs, are exposed, because the peer controls the response. Projects that use undici only for ordinary requests to their own services, or that never open EventSource connections, are less exposed, though upgrading still closes the gap.
| Product | Ecosystem | Affected | Fixed in |
|---|---|---|---|
| undici | npm | >= 6.5.0, < 6.29.1 | 6.29.1 |
| undici | npm | >= 7.0.0, < 7.30.1 | 7.30.1 |
| undici | npm | >= 8.0.0, < 8.12.2 | 8.12.2 |
| nodejs undici | vendor | >= 6.5.0, < 6.29.1 | 6.29.1 |
| nodejs undici | vendor | >= 7.0.0, < 7.30.1 | 7.30.1 |
| nodejs undici | vendor | >= 8.0.0, < 8.12.2 | 8.12.2 |
node -p "require('undici/package.json').version" in each project that depends on undici, and check whether the output falls in an affected range (6.5.0 to 6.29.0, 7.0.0 to 7.30.0, or 8.0.0 to 8.12.1).EventSource from undici to see whether the application keeps SSE connections open to peers it does not control.6.29.1, 7.30.1, or 8.12.2 (or later in the same major line).Each row is the first time that source carried this signal. The analyst’s rows are its own findings.
undici is an HTTP client library for Node.js. In versions 6.5.0 through 6.29.0, 7.0.0 through 7.30.0, and 8.0.0 through 8.12.1, its EventSource client can be driven to exhaust process memory by a malicious or compromised Server-Sent Events peer. By sending millions of tiny completed data fields with no blank event separator, or a single unfinished line split across many chunks, the parser retains a growing amount of per-field and per-chunk state that the byte-based maxEventSize and maxResponseSize limits do not bound, and because maxResponseSize is enforced on the compressed body before decompression, a small compressed response can expand into enough retained memory to terminate the process. An application only needs to maintain an EventSource connection to an untrusted peer, which controls only the response, and availability is the only impact. The issue is fixed in undici 6.29.1, 7.30.1, and 8.12.2, which bound the retained parser state independently of the byte limits, and users should upgrade to one of those versions or later. There is no workaround.
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