Live › vulnerability › CVE-2026-87029
Go to dashboardundici's decompress interceptor passes decompressed data to downstream handlers from zlib callbacks without catching exceptions, so a handler that throws (such as dump with maxSize) becomes an uncaught exception. A malicious HTTP server can send a small compressed body that expands past the limit and terminate any client process that uses this combination.
Summary written from the sources below. Check the originals before acting.
First seen by InfraStack 2026-10-27 19:04 UTC, 0h before NVD. All times on this page are UTC.
Only applications that use undici's decompress interceptor together with a response handler that throws during response processing, such as dump with a maxSize. Clients that call untrusted or third-party HTTP servers are the ones a malicious response can reach; apps that do not compose these interceptors can skip it.
| Product | Ecosystem | Affected | Fixed in |
|---|---|---|---|
| undici | npm | >= 7.15.0, < 7.30.1 | 7.30.1 |
| undici | npm | >= 8.0.0, < 8.12.2 | 8.12.2 |
| nodejs undici | vendor | >= 7.15.0, < 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 the project and compare against the fixed versions.undici and check whether code composes interceptors.decompress with interceptors.dump using maxSize.undici to 7.30.1 (7.x line) or 8.12.2 (8.x line).decompress interceptor with a response handler that throws, such as dump with a maxSize.Each row is the first time that source carried this signal. The analyst’s rows are its own findings.
undici's decompress interceptor forwards decompressed response data to the downstream handler from zlib stream event callbacks without catching exceptions those callbacks may throw. undici's engine converts a synchronous throw from a downstream handler into a per-request failure, but that protection is not in place when the throw happens asynchronously from a zlib callback. As a result, a downstream handler that throws by design, for example the built-in dump interceptor which throws when a response exceeds its maxSize, escapes as an uncaught exception and terminates the Node.js process.
A malicious or compromised HTTP server can crash any client that composes the decompress interceptor with dump (or another response handler that throws), by returning a small compressed body that decompresses to more than the configured limit. The compressed bytes on the wire are tiny, so only the decompressed size matters. If the application keeps the process alive with a global uncaught-exception handler, the affected request instead hangs until the body timeout.
Upgrade to undici 7.30.1 or 8.12.2.
Avoid composing the decompress interceptor with a response handler that throws during response processing (such as dump with a maxSize) until upgrading.
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